KR100704301B1 - Method for magnetizing alloy of transition metal and semiconductor by hydrogen injection - Google Patents

Abstract

The effect of hydrogen impurity on the electrical and magnetic properties of (II, TM) VI (TM = Mn, Co) Diluted Magnetic Semiconductor (DMS) was investigated through first-order pseudopotential calculation. It has been suggested that interstitial H can mediate strong near-ferromagnetic spin-spin interactions between adjacent magnetic fragments through the formation of bridge bonds. Results based on Monte Carlo simulation indicate that such spin-spin interactions mediated by H can induce high temperature ferromagnetics without creating free charge.

Hydrogen, lean magnetic semiconductor

Description

Magnetization method of transition metal alloy semiconductor by hydrogen injection method {METHOD FOR MAGNETIZING ALLOY OF TRANSITION METAL AND SEMICONDUCTOR BY HYDROGEN INJECTION}

1 is a diagram of a general electronic structure of a transition metal in a II-VI semiconductor.

2A is a view showing a hydrogen bridge bond state in ZnCoO.

2B is a diagram showing a Co-H trapped state in ZnCoO.

3 is a view of the electronic structure in the hydrogen bridge bond state in ZnCoO.

4 is a diagram of an electronic structure of an N-type ferromagnetic ZnMnO: H.

5 is a view of the electronic structure of the transition metal in the III-V semiconductor.

6 is a diagram of an electronic structure of ferromagnetic ZnCoO: H.

FIG. 7 is a plot of total electron density and total spin density around a spin parallel aligned Co—H _AB —Co complex.

8 is a view of the magnetic change with the temperature of ZnCoO by hydrogen injection.

The present invention relates to a lean magnetic semiconductor (DMS), and more particularly, to a magnetization method of II-VI-transition metal alloy semiconductor by a hydrogen injection method.

Extensive research has been conducted on lean magnetic semiconductors for applications in spintronic devices. Although many kinds of lean magnetic semiconductors have been found, there are still difficulties in practical application. A fundamental reason for limiting practicality is that the Curie temperature (Tc) associated with the ferromagnetic properties of the material is too low. Curie temperature, which determines the ferromagnetic properties of lean magnetic semiconductors, is known to be closely related to the concentration of charges in the material. According to the theory of double exchange interaction, lean magnetic semiconductors are used to obtain higher Curie temperatures. It is reported that it must have a charge concentration.

On the other hand, II-VI semiconductors such as ZnO are attractive lean magnetic semiconductor candidates because the solubility limit of magnetic ions is extremely high, and cobalt (Co) and manganese (Mn) are the magnetic impurities that are best dissolved in ZnO, and ZnCoO and ZnMnO Has been reported to show room temperature ferromagnetic properties. However, the magnetic properties of these materials are not well characterized in the lean magnetic semiconductors using II-VI semiconductors, and thus, there is no effective room temperature ferromagnetic material manufacturing technology required for practical application of these materials.

An object of the present invention is to consider the microscopic origins of magnetic properties in II-VI semiconductors, and to provide a lean magnetic semiconductor material having room temperature ferromagnetic properties consisting of II-VI-transition metals.

In addition, the present invention is a useful impurity capable of directly mediating strong near-field spin-spin interactions between magnetic ions in a lean magnetic semiconductor composed of II-VI-transition metals, without generating free charge, and high concentration of hydrogen. This is to report that can lead to high temperature ferromagnetic.

One of the important results revealed by the present invention is that in the case of II-VI-transition metal alloy semiconductors, spin interaction can be made by the bridging of hydrogen, so that the spindles of the transition metals are aligned parallel to each other with hydrogen in between. Can be.

The spin-bond interaction by hydrogen is so strong that magnetism can persist at high temperatures, ie at room temperature.

In particular, in general magnets, spin interaction occurs due to free charge concentration, but in the method of the present invention, spin interaction occurs due to hydrogen bridge bonding, and thus magnetization may be performed even in the absence of free charge.

Using this, it is possible to apply to the optical material. In the case of free electrons, light cannot penetrate into the material, so it is impossible to use it as an optical material.

Hydrogen spin interactions are also very near-field interactions that can be confined to at least Co-H-Co molecules, allowing for nanoscale spin manipulation because of the ability to define magnetism in nanoscale magnetic domains. Do.

1 is a diagram illustrating an electronic structure of a transition metal in a II-VI semiconductor.

In FIG. 1, the level represented by a dotted line indicates that the electron is empty, and the level represented by a single line indicates a state in which there is one charge. The level represented by a double line is an e level, which is double degenerate. Electrons in this level do not flow well.

The bottom dashed line indicates the t semi-bond level, where the electron orbit is towards the semi-bond site as shown in Figure 2, so that hydrogen can be easily trapped in this orbit.

FIG. 2A is a diagram showing a state of hydrogen bridge bonding in II-VI-transition metal semiconductor such as ZnCoO, and FIG. 2B is a diagram showing Co-H trapping state in ZnCoO.

In FIG. 2A, two adjacent Cos trap electrons of hydrogen between them to form Co-H-Co complex molecules. The t2g semibond orbital of Co extends to the interstitial site and bonds with hydrogen, thereby forming an H bridge bond at the semibond position. The chemical equation of the capture process is as follows.

H ⁺ + (Co-Co) ^-- > (Co-H-Co) ⁰ + 1.05 eV ------------------------ (1)

In the case of ZnCoO of FIG. 2B, when hydrogen is trapped in one Co, a reaction scheme in the case of being captured between Co and O atoms is as follows.

H ⁺ + Co ^-- > (H-Co) + 0.81 eV _________________________________ (2)

Therefore, it can be seen that hydrogen is strongly bound to Co.

3 is a diagram of an electronic structure in a hydrogen bridge bond state in ZnCoO.

When hydrogen is trapped at the t semibond level of Co, hydrogen combines with the t semibond orbit of the two transition metal ions and creates a new hydrogen energy level, which is the t orbit level of the original transition metal ion. And are significantly below the level of hydrogen. This level is particularly low when the Co spins are side by side. Therefore, the energy of the electron is greatly reduced, and the electron energy reduction effect combines two neighboring Co spins in parallel. In other words, Co-H-Co bonds can be ferromagnetically induced by the spin of two neighboring transition metals connected in parallel via hydrogen, and the new hydrogen levels are very deep and all electron energy bands become full or empty. Transport becomes difficult, and ZnCoO: H becomes ferromagnetic in an insulator state.

By obtaining the following equation through the first-principles total energy calculation, it was confirmed that the case where two Co spins are combined in parallel through hydrogen is more stable, and thus ferromagnetic can be easily induced.

E (↑, ↓)-E (↑, ↑) = 0.21 eV ------------------------------- (3)

This large energy difference indicates that the hydrogen-induced spin-spin interaction is strong enough to induce room temperature ferromagnetics.

Through this, it can be seen that the ferromagnetic spin pairs induced by hydrogen, together with the strong propensity of hydrogen to bond with the Co dimer, can realize room temperature ferromagneticity in ZnCoO through hydrogen incorporation. In addition, it can be seen that the energy level of the hydrogen bridge bond is deep, and all electron energy bands become full or empty, thereby making it difficult to transport charges, and thus ferromagneticity can be induced in the insulator state.

4 is a diagram of an electronic structure of an N-type ferromagnetic ZnMnO: H.

A hydrogen atom is placed between two adjacent Mn atoms in ZnO to enable t-semi-bonding or hydrogen bridge bonding of Mn. In this state, the Mn-H-Mn bond structure has a cell level below 0.05 eV of conduction band (CBM). to form a shallow level. In this case, the states in which the spins are coupled in parallel are more stabilized by 0.26 eV than in the states in the opposite direction. In other words, similar to Co, strong hydrogen mediated spin interaction is induced.

The spin interaction by this hydrogen bridge bond works in other II-VI and III-V semiconductors. In other words, when a bridging bond is formed between the t-semi-bond orbitals of the proximal transition metal (TM) atoms and hydrogen in II-VI or III-V semiconductors, strong spin interaction by hydrogen is induced.

In general, in (II, TM) VI lean magnetic semiconductors, when hydrogen is placed between two transition metal (TM) atoms, when the spindles of the two transition metals are parallel, the semibond t orbits of the two TMs and the hydrogen bridge bonds Since the electron energy is greatly reduced at this time, the TM-H-TM bonded state and the parallel spin bonded state become stable at the same time. In other words, hydrogen aligns two neighboring TM-spins in parallel, and when the transition metal concentration and the hydrogen concentration are sufficiently high, the hydrogen-mediated spin parallel alignment state is stabilized throughout the material, resulting in ferromagnetic.

This was confirmed by calculation for ZnCoO: H. It was confirmed that when the two spindles are parallel in the Co-H-Co coupling state, 0.1 eV is more stable than in the opposite direction. In other words, it was confirmed that hydrogen bridge bonds induce similar strong spin interaction in ZnCoS.

In general, Mn and Co in a II-VI semiconductor become ferromagnetic insulators. Hydrogen electrons form a bridging bond between two TM atoms to align spins, but all kinds of electron energy bands become full or empty, making them insulators with no free charge. In the case of Fe, since the electron partially occupies in the unbonded e orbit band, a weak conductor is formed through the ferromagnetic property of the hydrogen bridge and the charge in the e orbit band. Since the TM-d orbit in the e-band does not combine with the electron orbit of the semiconductor, the electrons of the e-band are not easily transported through the semiconductor. In the case of Ni and Cu, electrons are placed in the bridging by hydrogen, and electrons partially occupy the t-orbital band, and thus become conductors because of the ferromagneticity of hydrogen and the electron flow in the t-orbit. .

5 is a diagram showing the electronic structure of a transition metal in a III-V semiconductor.

Overall, it is similar to the electronic structure of the transition metal in the II-VI semiconductor of FIG. 1, and it can be seen that the electronic structure becomes the same when moved to the right by one space. As a result, in the case of III-V semiconductors, the effect of hydrogen injection is the same. Since Fe and Ni in group III-V semiconductors have the same electronic structure as Mn and Co in II-VI semiconductors, Ferromagnetic insulator, III-Co-V is a ferromagnetic weak conductor like II-Fe-VI, III-Cu-V is a ferromagnetic conductor by hydrogen, like II-Ni-VI.

On the other hand, the meaning of hydrogen in the present invention is very important.

Hydrogen is easily injected because it binds strongly with magnetic ions in the magnetic semiconductor.

One of the important implications of the present invention is that hydrogen is a useful impurity that can directly mediate strong near-ferromagnetic spin-spin interactions between adjacent transition metal ions, and high concentrations of hydrogen and high concentration transition metals are II-VI semiconductors III. When present in a -V semiconductor, it is confirmed that it can elicit high temperature ferromagnetic properties.

Through first principles calculations, the interaction between H and Co ions was examined to find that H influences the magnetic properties of ZnCoO in at least two aspects. Structurally, H forms a very stable Co-H-Co complex. Electronically, H opens up a new channel for ferromagnetic spin-spin interactions between such Co-Co dimers, with ferromagnetic spin-spin interactions by hydrogen than expected from the double-exchange interactions known by electrons. Much stronger.

Through the above research results, it was confirmed that the incorporation of H is an effective way of generating high-temperature ferromagnetic properties in ZnCoO, and the research process will be described in detail below.

The calculation method used in the present invention is based on the first-principle pseudopotential gross energy calculation within local spin density approximation. N. Troullier and JL Martins, Phys. Rev. Norm-conserving soft pseudopotential was made in the manner disclosed in B 43, 8861 (1991). An energy cutoff of 45 Ry was used for plane wave development. The atomic geometry was optimized through the use of the Hellmann-Feynman force. For the inspection of impurities and defects, the 36 atom superlattice model was used. The total energy was calculated using the (1/2, 1/2, 1/2) wave vectors of the Brillouin region of the superlattice model. To take into account the conditions in the same position and Zn -3 d Co d-3, semi-core (semicore) -3 Zn was d state trajectory certainly included in the calculation (orbitals). As a result of the inclusion of the d state, the calculated band gap was reduced to 0.92 eV, which is much lower than the value of 1.84 eV, which is indirectly included through the partial core modification. Underestimation of this gap is a known local density approximation error.

First, the energetics of H incorporation into ZnCoO is considered. As in ZnO, the interstitial H is the most stable shallow donorlike impurity at the bond-center (BC) site. Hydrogen is known to be found in significant concentrations in ZnO. In other words, there is considerable evidence that invasive H in ZnO is a very stable impurity and may be a major cause of the natural n-type properties of ZnO as a shallow dopant. In the wurtzite structure, two types of combinations can be distinguished. A combination of type-I along the c axis (BC _I ) and a combination of type-II along the other three axes (BC _II ). It was found that H (BC _II ) was more stable by 0.09 eV than H (BC _I ). This stable structure is described in Phys. Rev. Lett. 85, 1012 (2000); Phys. Rev. As disclosed in B 66, 165205 (2002), it is similar to that obtained by Van de Walle.

The enthalpy of formation of positively charged H at the most stable BC site is calculated from the equation below.

Ω (H ⁺ ) = E (H ^{+ in} ZnO) -E (ZnO) -μ (H2) / 2 + E _F ------------ (4)

Fermi Level E _F When is at the conduction band minimum (CBM) and valence band maximum (VBM), Ω (H ⁺ ) is calculated to be about 0.02 eV and 0.90 eV, respectively. The calculated binding energy of the n-type ZnO in the interstitial H is similar to that using the modified core part (core partial correction) obtained by Van de Walle treated with Zn-3 d states. E _F The smaller absolute value for Ω (H ⁺ ) when V is at VBM is that VBM moves up if the Zn-3 d trajectory is explicitly included in the calculation. These results for Ω (H ⁺ ) show that ZnO can be easily contaminated with H.

The stability of H in ZnCoO is enhanced by the hydrogen electrons being trapped in the Co-3 d- t _2g orbit in the energy bandgap. Various geometries for H-bonds with substituted Co were tested, and the concentration of dimers in Zn _{1 - x} Co _x O should be significant when x was large, so that the co-dimer (a pair of substitutions placed in the nearest cation site) The H bond with type Co ion) was also considered.

As in ZnO, the most stable binding site for substitution H around Co is the Co—O bond center (BC _II ) site, as shown in FIG. 6A. The site is 0.09 eV more stable than BC _I. The antibonding (AB) site of Co _Zn along the c-axis type-I Co-O bond is the most stable semi-binding arrangement for H. However, such AB sites are 0.19 eV less stable than BC _II sites. However, in the case of Co dimers in which two Cos are in close proximity, substitution at the common semi-binding position of the two Co ions forming the (Co-H _AB -Co) complex rather than at the BC site as shown in Figure 6b. Form H was found to be the most stable. The energy for that AB site is 0.25 eV lower than the energy for the BC array. In addition, the bond between H + and Co dimer is separated Co _Zn It was also found to be 0.22 eV stronger than atoms. In the (Co-H _AB -Co) complex, the Co-H spacing is 1.64 kPa and the Co-H-Co angle is 116 ° in the parallel spin-paired state. In the antiparallel state, the Co-H bond length is slightly longer to 1.71 kPa and the Co-H-Co angle is 114 °.

Since the deep Co- d level in the Co dimer can trap the separated donor electrons of the invasive H, consider the reaction where the ionized H atoms are captured by the dimer to form a Co-H-Co complex. (See Figure 6c)

H _i ⁺ + (Co _Zn -dimer) ^- → (Co-H-Co) ⁰ --------------------------- (5)

This reaction is a 1.05 eV exothermic reaction, indicating that the formation of (Co-H-Co) complexes can be significant in H-contaminated ZnCoO with high Co and H contents.

The most important result of the present invention is that when H is located between two nearest Co _Zn atoms to form a (Co-H _AB -Co) complex it induces a strong ferromagnetic spin-spin interaction between the Co atoms. .

It was also found that the parallel spin pair state of (Co-H _AB -Co) is much more stable (by 0.21 eV) than the antiparallel spin pair state. Such large energy differences indicate that the H-induced spin-spin interaction is strong enough to induce room temperature ferromagnetics. That is, the ferromagnetic spin pairs induced by H, together with the strong propensity of H to bond with the Co dimer, indicate that high temperature ferromagnetic properties can be realized in ZnCoO through H incorporation.

Another distinctive feature is that since H in the Co—H—Co complex produces a deep level, it does not contribute to the transport of charge. This gives an explanation for the low charge concentration in ZnCoO.

These two results can be understood by considering the electrical and magnetic properties of H in ZnCoO.

7A and 7B show the total electron density and total spin density around the spin parallel alignment (Co-H _AB -Co) complex. It should be noted that the spin on H is the opposite of that of the two Co ions, indicating that H is spin polarized and that the hydrogen orbit is coupled with the minor spin orbit of Co _Zn .

Examination of the electronic structure reveals how the parallel spin array is stabilized. In the parallel spin pair state, Co- has the highest energy level in the hydrogenic state.e _g Below the level lies a depth (by 2.22 eV). As shown in FIG. 7C, the H atom has two Co-3d- t _{2 g}  It combines with the minority spin trajectory to form a bridge bond. Such bridge bonds are stable only when the spins of the two Co ions are parallel. In the antiparallel spin pair state, as shown in FIG. 7D, the hydrogen state is represented by the H-s orbit and Co-.t _{2 g}  Originates from the coupling of the orbit and the level is Co-e _g It is located 0.65 eV below the state. Thus, the electron energy is much lower in the parallel spin pair state. Mediated by leg linkagedd Coupling stabilizes the parallel spin state.

The large binding energy between H and Co dimers can be well understood from the large decrease in electron energy due to the migration of electrons from the t _2g level of Co _Zn ⁻ to the deep hydrogen level. In the neutral charge state, since the hydrogenated level of the (Co-HAB-Co) complex is deep and stable, H does not contribute to the electrical conductivity. When combined with the Co dimer, but is not to be automatically ZnCoO the result that contamination with the free H (e) the charge or electron occupies the highest Co- t _2g level.

To further support the idea that strong ferromagnetic spin-spin interactions induced by H in (Co-H _AB -Co) complexes can lead to high temperature ferromagnetics, Monte Carlo simulations show the temperature dependence of magnetization of disordered ZnCoO Was simulated. Hamiltonian H _ij of the Heisenberg type = -JS _i S _j Was applied.

As a result, the parameter J was determined from the energy difference 0.21 eV between the spin parallel state and the antiparallel state for the nearest cation Co spin and 0.002 eV for the second closest Co _Zn dimer. In the case where a significant amount of Co atoms are dimerized, the dimerization of Co ions induced by H by the arbitrary distribution of Co atoms in the Urzate lattice is considered, and all Co dimers capture H atoms, resulting in strong spin-spin interactions. It is assumed to induce action.

The concentration of H relative to Co is described in the insert in FIG. 8A. The results of temperature dependence of the magnetization for the Zn _{0 .75} Co _{0 .20} O and Zn _0.85 Co _0.15 O (from an average value of the spin Co) is shown in Figure 8a. Penetration of Co dimers leads to long-range interactions, which results in high temperature ferromagnetics. The magnetization at high temperature is finite because the spin exchange interaction is locally enhanced between Co-H-Co complexes as well as between nearest Co ions. The calculation results for the Co alloy ratio dependency of the average spin near room temperature are shown in the insert in FIG. 8A. The average spin of Co increases as Co alloy ratio x becomes larger than 0.05, which indicates penetration behavior. High concentrations of Co are required for the penetration of strong spin-spin interactions leading to ferromagnetic alignment. Magnetization is enhanced at low temperatures. At high temperatures only the infiltrating clusters linked by H-mediated strong nearest interactions contribute to magnetization, and the small clusters that contribute to magnetization at low temperatures eventually average.

In addition, the H-mediated spin-spin interaction in ZnMnO was also discussed. Findings, t _2g mediated by H - The coupling of the 3 d levels to move the hydrogen form level down e _g level, and such hydrogen-form state ZnMnO: - that it is possible to induce a spin interaction spin even in H Figured out. The spin parallelism of the (Mn-H _AB -Mn) geometry is calculated to be 0.22 eV more stable than antiparallel, indicating that the H effect is also important for the ferromagnetic properties of ZnMnO. This is the basis for explaining that the reported magnetic properties of ZnMnO are similar to that of ZnCoO, in particular in the temperature dependence of magnetization.

In addition, the hydrogenated state is calculated to be 0.05 eV further below CBM, which may explain the n-type conduction in ZnMnO. Spin splitting of Mn 3-d is one present in the energy level of the much larger and, minority spin state of the Mn-3 d is band gap than that of the Co 3-d, a much higher position compared to that of Co. This is because the level of t _2g - 3 d in Mn before hydrogen bonding is much higher than the level of t _2g - 3 d in Co.

On the other hand, H effects in other II-IV semiconductors such as ZnCoS are also discussed. Since the atomic structure and the electronic structure are similar to those in ZnCoO, strong spin-spin interactions are expected, which are correspondingly induced by H in ZnCoS. The spin parallel state of (Co-H _AB -Co) is calculated to be 0.10 eV more stable than the antiparallel state. This indicates that spin interactions promoted by H can occur in other II-IV semiconductors if high concentrations of H can be obtained between magnetic impurities.

The strong spin-spin interaction induced by invasive H is specific to hydrogen. In the case of lithium (Li) having an electronic structure such as hydrogen, ferromagneticity was not induced. Although Li is electronically similar to H in that it has only one electron in its chemically active s orbit, it does not form a bridge bond coupling of two d orbits, and a stable bond site for Li is significantly different from that for H. Away. Therefore, the influence on the magnetic properties of ZnCoO is very different. In the case of lithium in ZnCoO, when the Li is placed between two Co ions, the spin-spin interaction induced by the invasive Li at the common semi-bond site of the Co dimer was tested. It was found to be more stable by 0.05 eV than. In other words, Li does not form a bridge bond unlike H, and thus does not cause strong ferromagnetic spin interaction.

Although H can induce strong spin-spin interactions suitable for high temperature ferromagnetics in ZnCoO , it also excludes the possibility of ferromagnetics through double exchange interactions resulting from the presence of extra electrons in the Co-3 d- t2g band. You can't. Even if there is only one surplus electron per two Co ions, the parallel spin pair state of the two nearest Co _Zn ions is 0.08 eV more than the antiparallel spin pair state due to the double exchange interaction in the t _2g band. Stable When the Co _Zn ion is placed in the second closest cation site, the energy difference is reduced to 7 meV. The temperature dependence of magnetization (see FIG. 8B) calculated using the calculated spin interaction energy is similar to experimental data indicating that T _c of ZnCoO is about 300K.

When hydrogen is injected into II-VI-transition metal semiconductors or III-V-transition metal semiconductors, magnetism can be maintained even at high temperatures (room temperature) because the spin-bond interaction by hydrogen is very large.

In general magnets, spin interaction occurs due to free charge concentration, but in the present invention, spin interaction occurs due to hydrogen bridge bonding, and thus magnetization is possible even in the absence of free charge.

A general magnet with free electrons is difficult to use as an optical material because light does not penetrate into a material. However, in the case of a magnetic semiconductor magnet produced by hydrogen injection of the present invention, since magnetism is generated without free charge, magnetic optical It can be applied to materials.

Hydrogen spin interactions are also very near-field interactions that can be confined to at least Co-H-Co molecules, allowing for nanoscale spin manipulation because of the ability to define magnetism in nanoscale magnetic domains. Do.

Molecular magnets or nanomagnets can be provided based on the above results, and the above results are also applicable to fields such as MRAM manufacturing.

Claims (12)

Providing a transition metal alloy semiconductor; Injecting hydrogen into the alloy semiconductor, Hydrogen electrons are trapped in semi-bond levels between atoms constituting the transition metal alloy semiconductor to form a composite molecule, and the bond trajectory is extended to the intrusion site to form hydrogen bridge bonds at the semi-bond positions, thereby generating new hydrogen energy. Alloying the alloy semiconductor by magnetizing the process by making a level, by causing the two adjacent transition metal spindles to be coupled in parallel by hydrogen by the new hydrogen energy level; Magnetization method. The method of claim 1, The transition metal is magnetized method of the alloy semiconductor, characterized in that selected from the group consisting of Mn, Fe, Co, Ni, Cu. The method according to claim 1 or 2, The transition metal alloy semiconductor is a magnetization method of the alloy semiconductor, characterized in that the II-VI- transition metal alloy semiconductor. The method according to claim 1 or 2, The transition metal alloy semiconductor is a magnetization method of an alloy semiconductor, characterized in that the III-V-transition metal alloy semiconductor. A transition metal alloy semiconductor magnetized by the method of claim 1. delete delete The method of claim 5, The transition metal alloy semiconductor has a structure of (II, TM) VI: H containing a high concentration of hydrogen and transition metal ions in a II-VI semiconductor. The method of claim 5, The transition metal alloy semiconductor has a structure of (III, TM) V: H containing a high concentration of hydrogen and transition metal ions in a III-V semiconductor. A molecular magnet, which is magnetized by the method of claim 1, contains a low concentration of hydrogen, has a structure of TM-H-TM, and is formed in a II-VI semiconductor. The method of claim 10, The TM is a molecular magnet, characterized in that Co. The method of claim 10, Molecular magnets, characterized in that TM is Mn.

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