Magnetothermal instability in the organic layered superconductorκ−(BEDT-TTF)2Cu(NCS)

Abstract

We have studied the magnetothermal instability in -͑BEDT-TTF͒ 2 Cu͑NCS͒ 2 by means of measuring the temperature change in the sample. We report the remarkable temperature spikes due to the flux jumps and the preceding temperature oscillations in the vortex solid state. These dependences on the sweep rate are almost consistent with the conventional theory based on the Bean model. The temperature dependences of the flux jump suggest that the melting transition from the vortex solid to the liquid phase at low temperatures is not driven by thermal fluctuations, but rather by quantum ones. The small temperature fluctuations observed at very low temperatures imply the dendritic vortex distribution in this salt.

Suppression of Superconductivity by Nonmagnetic Disorder in Organic Superconductor κ-(BEDT-TTF)2Cu(NCS)2

“…46 The sharp spike structures observed inside the hysteresis loop result from the flux jumps appearing in the nonequilibrium vortex state upon sweeping the magnetic field. 31,47,48 In the X-ray-irradiated sample, as shown in Fig. 3(b), the torque curves in the superconducting region show a measurement-to-measurement variation although the same sample is measured with increasing irradiation dose.…”

Fulde–Ferrell–Larkin–Ovchinnikov and vortex phases in a layered organic superconductor

“…When the field is perpendicular to the layer, we observe successive sharp spikes (rapid heating) due to flux jumps below H c2 (see SI D) and quantum oscillations (QOs) in the high field normal state (see SI E). The flux jumps are associated with precursor oscillations and overshoot cooling, 26 which are clearly distinct from the peaks at H peak1 , H peak2 , and H peak3 . Figure 4a presents the field angle dependence of H irr , H peak1 , H peak2 , and H peak3 obtained from the MCE measurements.…”