Magnetic Study of the Lower Critical Field of Organic Superconductor λ-(BETS)₂GaCl₄

Abstract

The lower critical field of type-II organic layered superconductor λ-(BETS)2GaCl4 has been estimated by magnetic measurement. In this study, the demagnetization factor of a needle-like sample shape has been taken into account for the measurements by applying external field, parallel and perpendicular to the conducting plane. The lower critical field for the field perpendicular to the conducting plane is 8(1) G, convincing the previous study. This estimation allows us to predict the ideal external field that should be applied for London penetration depth measurement by using muon-spin rotation (SR) spectroscopy.

Anisotropy of Lower Critical Field in Organic Layered Superconductor λ-(BETS)₂GaCl₄

“…The applied field for the field-cooling FC data was 1 Oe. In comparison with the similar measurement under 1 Oe with the magnetic field perpendicular to the conducting plane [10], the signal we observed was about 10 times smaller.…”

“…The dimension of the sample was 0.09 × 0.16 × 1.5 mm 3 and the mass was 0.127 mg, and the sample setup was reported in the Ref. [10]. The sample setup allowed us to measure one single crystal in the direction of applied field parallel and perpendicular to the conducting plane.…”