SU1515115A1 - Method of determining hall quantum resistance - Google Patents

Abstract

The invention relates to electrical measuring equipment and can be used in metrology for reproducing the value of the quantum Hall resistance, as well as in experimental physics. The aim of the invention is to improve the accuracy of the method for determining the quantum resistance of a Hall. In this method, a transport current of charged carrier particles is passed through channel 1 of a Hall converter with a two-dimensional electron gas between current electrodes 2. The Hall transducer is placed in a perpendicular magnetic field. Electromotive Hall force is induced between Hall electrodes 3,4,5 and 6,7,8. At the same time on the electrodes 4 and 7, the value of the Hall EMF will be two times greater than with a single passage of carriers. The method makes it possible to reduce the influence of thermoEMF and to increase the accuracy of measurements of the quantum Hall resistance by 1.5 - 2 times compared with the known technical solutions. 3 il.

Description

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the current electrodes 2 pass the transport current of the charged carrier particles. The Hall transducer is placed in the Perpendicular magnetic field. Between the HOPLOR electrodes 3, 4, 5 and 6, 7, 8 the Hall electromotive force is induced. At the same time on the electrodes 4 and 7 the value of the Hall voltage will be d) than with a single pass media. The method makes it possible to reduce the influence of thermoEMF and increase the accuracy of measurements of the quantum Hall resistance by 1.5–2 times in comparison with the known technical solutions. 3 il.

The invention relates to electrical measuring equipment and can be used in metrology for reproducing the value of quantum Hall resistance (CSC = conventional abbreviation), as well as in experimental physics to refine the values of fundamental physical constants based on macroscopic quantum effects.

The aim of the invention is to improve the accuracy.

FIG. current lines and equipotentials in the region of the channel of the quantum Hall transducer are presented when the current is removed from the channel and repeated its injection; Fig. 2 is the same, with a single pass through the channel carriers; Fig. 3 is a schematic of a device for measuring CSH.

According to the proposed method (FIG. 1), a transport current of charged carriers (for example, from an external power source) is passed through the Hall 1 transducer with a two-dimensional electron gas (2 MEG) between the current electrodes 2, the Hall transducer is placed in a perpendicular magnetic field. Between the Hall electrodes 3-5 and 6-8, Hall electromotive force (EMF) is induced.

After the passage of the charge carrier section of the channel 1 in the region of the measuring electrodes 4, 7, the transport current rises from the channel at the location of the electrode 5 on the side face of channel 1. This current is re-injected into channel 1 in the region of electrode 6 on the opposite side face of channel 1 to section 4.7.

Thus, through the cross section of channel 1 at the location of the cold

LOVO measuring electrodes 4, 7 the same transport current of charged carriers passes two times, which leads to the appearance on the measuring electrodes

4, 7 of the Hall emf, the value of which is exactly two times greater than with a single passage of carriers, Vyshod and current injection through the side faces of the channel can be carried out at the temperature of the liquid helium, therefore the thermopower value in the measuring electrode circuit does not change. This reduces the failure due to the influence of

thermoEMF on the measurement result,

Injection and current output from the channel Through the side faces can be carried out, for example, by introducing a superconducting jumper between the electrical

Dami 5 and 6, Since between the opposite sides of the transducer in the absence of the indicated jumper, see FIG. 2) the Hall voltage is present, the shorting of the electrodes

5 and 6 leads to current flow between them. The distribution of the power lines of the current density vector in a conducting medium is governed by the Makewell equations; therefore, the divergence of the current density vector is zero, i.e. power lines cannot intersect. This means that the entire transport current exits channel 1 through electrode 5, and all the current injected into channel 1 through electrode 6 reaches the current electrode 2. For the same reason, no carrier current can flow in channel 1 between electrodes 6 and 5 Consequently, in 2MEG

Channel 1 forms two independent regions with carrier transport current having the same value, leading to a doubling of the value of the Hall EMF.

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Fig. 1 conventionally shows the direction of the magnetic induction vector B. When changing the direction of the magnetic field, the transport current should be removed from channel 1 not from electrode 5, but from electrode 8, i.e. in accordance with the direction of displacement of charged carriers to the side face of channel 1, according to the direction of the intensity vector of the transverse electric field, determined by the vector product of the velocity of the carriers and the induction of the magnetic field. In this case, the current outputted through the electrode 8 must be introduced into channel 1 through contact 3, and electrodes 5 and 6 must be open.

The quantizing of the converter is achieved by minimizing the voltage drop inside the channel in the longitudinal direction. For this, electrodes 3, 4, or 7, 8 can be used. The circuit of the device for measuring the CSX (Fig. 3) does not change. However, since the EMF of the converter is doubled in comparison with the known solutions, the nominal value of the resistance measure in the device must also be doubled.

In the described switching on, when measuring the CSR without changing the value of the transport current in the circuit of current electrodes 2 of the converter, the Hall voltage doubles. Consequently, a doubles the equivalent value of CCX. This allows the comparison of the SCC measured by known methods with the SSC measured by the proposed method without changing the value of the transport current and the plateau number, i.e. numbers of filled Landau levels. This opens up a new possibility of detecting systematic faults and increases the accuracy of measurements.

FIG. The equipotentials and lines of the current of the converter are constructed from the experimental data obtained from the study of quantum Hall converters. The SchP-structure of ra-doped silicon — controlled by a gate voltage was used as a converter. The converter is placed inside a superconducting magnetic solenoid. With an induction of 10 T at a temperature of 4.2 K.

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A transport current of 5 μA from the mercury elements was passed through the converter. Quantization mode was achieved by adjusting the gate voltage to the minimum of the longitudinal voltage. In the experiment, the adjustment was made to a plateau corresponding to four filled levels

0 Landau.

Testing of the layout showed that during current output through the side face of the channel and its repeated injection through the opposite side face, the Hall emf doubles with high accuracy. The difference in the values of the COX without injection and with the injection of carriers (taking into account the half value of the COX) did not exceed, i.e. lay

0 within the limits of measurement experiment.

Thus, the output of the transport current from the channel area through the side face after the passage of the 5 section cross section with the Hall

electrodes and repeated injection of the extracted current into the channel to the specified cross section allows to reduce the influence of thermoEMF by double measurements

0 (without injection and with injection) and improve the accuracy of measurements of COX by 1.5–2 times in comparison with the known technical solutions. Formula inventions

The method of determining the quantum Hall resistance, which consists in the fact that the current of a given magnitude is passed through the channel of the quantum Hall

0 a transducer placed in a transverse constant magnetic field measures the Hall electromotive force, determines the value of the Hall's quantum resistance with respect to the Hall electromotive force to a given current value, which, in order to improve the determination accuracy, before measuring the Hall electromotive force

Q output from a quantum Hall transducer across a side face of a current of a given magnitude after the passage of the charge carrier across the cross section of the potential electrodes of the quantum

- a Hall converter and inject a current of a given magnitude through the side face of the quantum Hall converter before they pass the cross section of potential electrodes. -,

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Claims (1)

Claim those. lay measuring Method for determining the quantum Hall resistance, namely, that a current of a given value is passed through a channel of a quantum Hall transducer placed in a transverse constant magnetic field, the Hall electromotive force is measured, the value of the quantum Hall resistance is determined from the ratio of the Hall electromotive force to a given current value, different I mean that, in order to improve the accuracy of determination, before measuring the Hall electromotive force, they are removed from the quantum hall ovskogo transducer through the side face current of a predetermined value after the passage cross section of the charge carriers electrode potential and quantum Hall transducer injected current of a predetermined value through the side face of the quantum Hall transducer section before passage of potential electrodes. - 6.453.20 (1 ° 32 P32 32 * 8, ³ Fig. 1