JPH02176531A - Temperature sensing element - Google Patents

Abstract

PURPOSE:To fine the element and to contrive the facilitation of discriminating whether a temperature is in a prescribed area or not by providing a ferromagnetic body, a superconductive ring and an electrode. CONSTITUTION:The element is provided with a ferromagnetic body 1, a first superconductive ring 3 provided so as to surround the ferromagnetic body 1 in a state insulated electrically against the ferromagnetic body 1, and a second superconductive ring 5 provided so as to surround the ring 3 in a state insulated electrically against the ring 3 and having a Josephson junction. Also, this element is provided with a pair of electrodes 7a, 7b provided on the ring 5. In this state, by utilizing the temperature dependency of spontaneous magnetization of the ferromagnetic body 1, a temperature is sensed by a magnetic flux for passing through the ring 5 formed by the ferromagnetic body 1 and the ring 3. Subsequently, by utilizing a magnetic flux - voltage characteristic of the ring 5 having a Josephson junction in the case when a constant bias current is allowed to flow between the electrodes 7a, 7b, a sensed temperature is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a temperature sensing element that can be miniaturized and has a simple structure.

[Prior Art and Problems to be Solved by the Invention] Conventional temperature sensing means include the following.

■Utilizes the temperature dependence of density (thermal expansion) in specific substances.

■Things that utilize the temperature dependence of thermoelectromotive force in specific substances (thermocouples, etc.).

■Utilizes the temperature dependence of electrical conductivity of specific substances.

Among these, the disadvantage of (2) is that it is difficult to miniaturize and requires a means to convert density displacement into electrical displacement when used as an electronic device. Also, ■
There is also a certain limit to miniaturization, and ultra-fine miniaturization is difficult. Furthermore, the temperature dependence of the electromotive force is generally nonlinear, making it difficult to use, and the sensitivity is low at extremely low temperatures. Regarding (2), if the temperature characteristics are nonlinear and the material undergoes a superconducting transition,
The drawback is that temperature information cannot be obtained below the critical temperature.

Furthermore, in any of the above techniques, in order to determine whether the temperature is within a certain range (that is, for example, 100°C or higher and 200°C or lower), a continuous quantity (in the case of ) is a value corresponding to the temperature range (■ is the range of electrical conductivity) or not.

This invention was made in view of the above circumstances, and is capable of miniaturization, is capable of determining whether or not the temperature is within a certain range, and is capable of sensing temperatures even in the extremely low temperature range. The purpose of the present invention is to provide a temperature sensing element that can be used.

[Means for Solving the Problems] A temperature sensing element according to the present invention includes a ferromagnetic material, and a first ferromagnetic material provided to surround the ferromagnetic material in a state of being electrically insulated from the ferromagnetic material. a second superconducting ring that is electrically insulated from the first superconducting ring and has a Josephson junction and is provided to surround the first superconducting ring; and a pair of electrodes provided on the second superconducting ring.

[Function] According to such a configuration, the temperature dependence of spontaneous magnetization of the ferromagnetic material is utilized to reduce the magnetic flux formed by the ferromagnetic material and the first superconducting ring and penetrating the second superconducting ring. The temperature can be sensed by using the magnetic flux-voltage characteristics of the second superconducting ring including the Josephson junction when a constant bias current is passed between the electrodes.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing a temperature sensing element according to a first embodiment, and FIG. 2 is a plan view thereof. In the figure,
Reference numeral 1 is a ferromagnetic material whose magnetization is in the direction indicated by arrow A (direction perpendicular to the plane of the paper in FIG. 2). Around this ferromagnetic material 1, a first insulator 2, a first
A superconducting ring 3, a second insulator 4, and a second superconducting ring 5 are provided in this order. The outermost superconducting ring 5 is separated into a portion 5a and a portion 5b by two third insulators 6, and has a Josephson junction. Electrodes 7a are provided on the outside of these portions 5a and 5b of the superconducting ring 5, respectively.

7b is provided. Note that the superconducting critical temperature of the second superconducting ring 5 is higher than that of the first superconducting ring 3. Further, the critical temperature of the second superconducting ring 5 is 23 degrees higher than the Curie temperature of the magnetic material 1.

Next, the temperature sensing principle of the temperature sensing element configured as described above will be explained by dividing it into two parts: H degree-magnetic flux characteristics and magnetic flux-voltage characteristics.

It is the portion consisting of the magnetic body 1, the first insulator 2, and the first superconducting ring 3 that is involved in the temperature-magnetic flux characteristics. FIG. 3 is a graph showing the temperature dependence of the spontaneous magnetization of the ferromagnetic material 1. FIG. As you can see from this figure, the Curie temperature "c"
Spontaneous magnetization decreases rapidly near urio. FIG. 4 is a graph showing the temperature dependence of the magnetic flux Φ passing through the superconducting ring 5 formed by the ferromagnetic material 1, the insulating material 2, and the superconducting ring 3 forming a Josephson junction. Here, Φ
The material, size, structure, etc. of the magnetic body 1 are adjusted so that the range of change is 0≦Φ≦Φ0. The reason why the magnetic flux Φ steps to Φ0 at the superconducting critical temperature of the first superconducting ring 3 is because the superconducting current flows and the magnetic flux is quantized.

The second superconducting ring 5 and the third insulator 6 forming the Josephson junction are involved in the magnetic flux-voltage characteristics. FIG. 5 shows a constant bias current I at a temperature lower than the critical temperature of the superconducting ring 5.

3 is a graph showing the relationship between magnetic flux and inter-electrode voltage when . When the magnetic flux penetrating the superconducting ring 5 having the insulator 6 has a value that is an integral multiple of Φ0, it takes a certain minimum value vo.

FIG. 6 is a graph showing the temperature-voltage characteristics obtained from FIGS. 4 and 5. In this case, the temperature T must be lower than the critical temperature To of the superconducting ring 5 in order for this element to operate.

As shown in FIG. 6, if the temperature T is V-Vo, then T≦”
rc or "cur1c≦T≦To, and V>v. Then, it can be seen that T c −< T < T c u r Ho. That is, by measuring the voltage between the electrodes 7a and 7b, the temperature can be sensed.

Next, a second example will be described. FIG. 7 is a plan view showing a temperature sensing element according to a second embodiment. An insulator 12 and a first superconducting ring 13 are provided in this order around the first magnetic body 11.
4, a second insulator 15 and a second superconducting ring 16 are formed in this order. These magnetic materials 11
, an insulator 12, and a superconducting ring 13,
and magnetic material 14, insulator 15, and superconducting ring 16
These structures are constructed in the same manner as the magnetic body 1, insulator 2, and superconducting ring 3 of the first embodiment, and these structures are arranged in parallel at appropriate length intervals. The third insulator 17 is provided around the first superconducting ring 13 and the second superconducting ring 16 to insulate them from each other.

A third superconducting ring 18 is provided around the third insulator 17 . This third superconducting ring 18 is separated into a portion 18a and a portion 18b by two fourth insulators 19, and has a Josephson junction. Electrodes 20a are provided on the outside of these portions 18a and 18b of the superconducting ring 18, respectively.

20b is provided. Note that the magnetic material 11 and the magnetic material 1
Curie temperature Tcurlel, T which is different from 4
cuclc2 (Tcurlel<” cucle2)
The first superconducting ring 13, the second superconducting ring 16, and the third superconducting ring 18 have different critical temperatures T(1, T(2・T(3(T(1<TC2< T(3).These T.url.11T cuolc2
, TCl, TC2, and TC3, TC1<”cur
There is a relationship of lol<TC2<"cuolc2<TC3.

In this case, the temperature dependence of the magnetic flux is as shown in FIG. 8, and the temperature dependence of the voltage between the electrodes 20a and 2Ob is the same as shown in FIG. 5, so the temperature-voltage characteristics are shown in FIG. 9. It becomes like this. In other words, if V>Vo at TTC3, the temperature T is TCI<"<"curroll or Tc
2kuTkuT. ,. If it is Tc2 and V-V, it can be seen that it is a value other than that. In this way, by increasing the number of magnetic materials and superconductors, it is possible to increase the number of stages in the temperature range where V>Vo.

In the above examples, the characteristics of a single element were shown, but by using several such elements, for example, the temperature range of V-Vo could be changed to "
If we treat the temperature range of 0'' and V>vo as a bit signal with rlJ, we can divide the predetermined temperature range into several parts and assign numerical values to each part, as shown in Figure 10. , it is possible to obtain a temperature sensing element that also has an analog-to-digital conversion function. By doing so, it is possible to digitally output which temperature range the sensed temperature is within, without using any other means.

[Effects of the Invention] According to the present invention, since the temperature sensing element 1114 is made up of the ferromagnetic material, the superconducting ring, and the electrode, it is possible to miniaturize the element. Furthermore, since a predetermined temperature range is sensed by voltage changes between electrodes, it is easy to determine whether the temperature is within the 2A degree range. Furthermore, since it uses superconductivity, it can also sense extremely low temperatures. Furthermore, there is an advantage that the output voltage can be treated as a bit signal, and it can be used in a correction circuit based on temperature of an LSI.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a temperature sensing element according to a first embodiment of the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a graph showing the temperature dependence of spontaneous magnetization of a magnetic material, and FIG. The figure is a graph showing the temperature dependence of the magnetic flux Φ penetrating a superconducting ring having a Josephson junction in the first embodiment, FIG. 5 is a graph showing the relationship between the magnetic flux Φ and the voltage between the electrodes, and FIG. is the first
FIG. 7 is a plan view showing the temperature sensing element according to the second embodiment of the present invention, and FIG. 8 is a graph showing the temperature dependence of the interelectrode voltage in the second embodiment. A graph diagram showing the temperature dependence, TS9 is a graph diagram showing the temperature dependence of the inter-electrode voltage in the second embodiment, and the 10th
The figure shows signal bits when two temperature sensing elements of the present invention are combined. 1.11.14; Magnetic material, 2.4.6.12゜15.1
7, 19; Insulator, 3, 5. 13. 16° 18; Superconducting ring, 7a, 7b, 2. Oa. 20b; electrode.

Claims (1)

[Claims] a ferromagnetic material, a first superconducting ring provided to surround the ferromagnetic material while being electrically insulated from the ferromagnetic material; A second superconducting ring having a Josephson junction is provided to surround the first superconducting ring in an insulated state, and a pair of electrodes are provided on the second superconducting ring. Features a temperature sensing element.