DOI: 10.1051/jp1:1994104
J. Phys. I France 4 (1994) 159-166

High-field magnetotransport of organic conductors (BEDT-TTF) ₂TlHg(XCN) ₄ With X = S and Se

M. V. Kartsovnik¹, D. V. Mashovets², D. V. Smirnov², V. N. Laukhin³, A. Gilewski^{4, 5} and N. D. Kushch<sup>3

1</sup>  Institute of Solid State Physics, Chernogolovka, MD, 142432 Russia
²  A. F. loffe Physical Technical Institute, St-Petersburg, 194021 Russia
³  Institute of Chemical Physics, Chernogolovka, MD, 142432 Russia
⁴  MAG-NET Laboratory, ul. Gajowicka 95, 53-529 Wroclaw, Poland
⁵  International Laboratory of Strong Magnetic Fields and Low Temperatures, ul. Gajowicka 95, 53-529 Wroclaw, Poland

(Received 26 July 1993, accepted 3 September 1993)

Abstract
High field magnetoresistance of layered organic metals (BEDT-TTF) ₂TlHg(XCN) ₄ with X = S and Se has been studied using pulsed magnetic fields. Sharp negative slope and strong hysteresis of the magnetoresistance of (BEDT-TTF) ₂TlHg(XCN) ₄ found between about 11 and 27 T suggest a first-order phase transition to occur at those fields. Two different types of angular magnetoresistance oscillations corresponding most likely to different electronic states are observed in the low- and high-field phases, respectively. In contrast, the classical magnetoresistance of the salt with X = Se is found to be smoothly growing with the field increase. The obtained results are compared with those reported earlier on the (BEDT-TTF) ₂MHg(SCN) ₄ salts with M = K and NH ₄ and discussed in the framework of the model proposed recently for the low-temperature electronic state of (BEDT-TTF) ₂TlHg(SCN) ₄.

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