Manipulating superconductivity using a & # 39; mechanic & # 39; And a & # 39; electrician & # 39;



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Manipulating superconductivity using a & # 39; mechanic & # 39; And a & # 39; electrician & # 39;

Before applying the mechanical stress or electric voltage, the organic correlated material stays in an insulating state, since the electrons have been snugly plugged into their "reserved seats" at the molecules. After the gate voltage is applied, the number of electrons changes and gives rise to empty (hole-doped) or standing (electro-doped) seats. The mechanical stress is the change in the distance between the seats. The appropriate combination of these interferences determines the material to be a superconductor. Credit: Nissan / IMS

Highly correlated materials such as captured high-temperature superconductors, superconductivity can be controlled or by changing the number of electrons or by changing the kinetic energy, or energy transfer, from electrons into the system. Although a large number of highly correlated materials have been examined with different parameters to understand the superconductivity mechanism, the range of parameter control is always limited. A versatile experimental method of achieving simultaneous control of the number and energy of the electrons has long been desired.


A flexible electric-double-layer transistor (EDL), or "correlated" transistor, connected to an organic highly correlated material (Figure 1) by researchers at Rike, the Institute for Molecular Science (IMS), the Nagoya University and the Toho University. The number of electrons can be controlled by gate spectra of the EDL, and the transport energy of electrons can be controlled by bending the base of the beam. They have found that the system has changed from an insulator to a superconductor in both cases of increasing and decreasing electron numbers. Conditions for the superconducting states in the above two cases, however, were found to be fundamentally different. In addition, another superconducting state emerges when the substrate is bent. The present result is published online on Science Advances May 10, 2019.

Researchers fabricated by the slab using a crystal of the organic highly-corroded material, made from bed-tft (bis (ethylenedithio) tetrathaulvalvalene) (Figure 1). By applying the crystal gate gate voltage, the number of electrons can be increased (electron doping) and decreased (hole doping). This edible device is flexible, and the transport energy can be controlled by the application of mechanical force (tension) from the back of the eddy. The researchers successfully controlled superconductivity in an identical pattern by precisely changing both gate voltage and voltage.

Manipulating superconductivity using a & # 39; mechanic & # 39; And a & # 39; electrician & # 39;

Resistivity is shown by color. The insulator area (red) is surrounded by the superconducting regions (blue). The focus of the insulating and superconducting routers varies between the negative and positive ranges of the gate voltage. The form of the electron-ducted superconducting area (Esk) has been found to be quite anomalous. Credit: Nissan / IMS

Figure 2 shows the regions of superconducting states. The abscissa shows the gate voltage which corresponds to the number of doped electrons. The ordinate shows the tension applied to the device by bending. Down the ordinate, the electrons move more easily because of the kinetic energy of electrons. The region of the insulating state (red) is surrounded by regions of superconducting states (blue). Two superconducting areas on the left and right sides of the insulating area are significantly different in shape. 2. In particular, superconducting states emerge with an increasing number of electrons (the right side of Figure 2) showing remarkable behavior that the state suddenly appeared with a few percent increase from the number of electrons and disappeared with the addition of excess electrons. The superconducting states can be obtained by increasing and decreasing electron numbers. However, the features of the two states have been found to be fundamentally different.

The two-dimensional phase diagram (Figure 2) is thus obtained using the one pattern. The diagram shows the nature of the superconducting phase transition, which is anticipated for data collected in many different samples before the device is released. Therefore, the newly developed experimental method accelerates to obtain phase diagrams. More fundamentally, drawing the full phase diagram of the same pattern enables us to get more reliable results regardless of the effects of impurity and difference in crystal structures.

This experimental method can be applied to a variety of organic corrugated materials. One interesting example is the quantum spins liquid in which the directions of electron spins move randomly even at 0 Kelvin. Experiments on the Quantum Spin fluid will reveal the relationship between superconductivity and magnetism (arrangement of electron spins). It is also noticeable that the phase diagram of strong correlated electronic system is a significant target of quantum simulators. The present result provides a standard solution for the newly developed calculation methods.


Topological material shows superconductivity and not just in its surface


More information:
"Two-dimensional ground-state mapping of a Mott-hubbard system into a flexible field-effect device" Science Advances (2019). DOI: 10.1126 / sciadv.aav7282, https://advances.sciencemag.org/content/5/5/eaav7282

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National Institutes of Natural Sciences

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Manipulating superconductivity using a & # 39; mechanic & # 39; And a & # 39; electrician & # 39; (2019, May 10)
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