Microscopic Observation of π Spin Polarization by d Localized Spin in λ Type BETS Based Organic Superconductors

• Published in: Crystals (Basel) Vol. 10; no. 11; p. 1055
• Main Authors: Hiraki, Ko-ichi, Takahashi, Toshihiro, Akiba, Hiroshi, Nishio, Yutaka, Zhou, Biao
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.11.2020
• Subjects: (BETS)2Fe1−xGaxCl4; Dependence; Electrolytes; Exchanging; FISC; Heat; Low temperature; Magnetic fields; NMR; Nuclear magnetic resonance; Organic superconductors; Polarization (spin alignment); Single crystals; π-d interaction
• ISSN: 2073-4352; 2073-4352
• DOI: 10.3390/cryst10111055

In this study, 77Se NMR measurements were carried out to detect the π spin polarization of the organic BETS (BETS = Bis(ethylenedithio)tetraselenafulvalene) molecule of the field induced superconductor, λ-(BETS)2Fe1−xGaxCl4, which shows a superconducting transition at relatively low magnetic field compared to the non-doped λ-(BETS)2FeCl4. From the analysis of the NMR spectrum at low temperature, it was clarified that the exchange interaction between π and 3d spins in the Ga doping system is smaller than that in the Fe salt. It is also clarified that the conduction π spins feel the “averaged” exchange field from the localized 3d spins at the dilute Fe sites.