The Origin of Anomalous Angular Dependent Magnetoresistance Oscillation Effect in<b>α</b>-(BEDT-TTF)₂KHg(SCN)₄

Abstract

Angular dependent magnetoresistance oscillation (ADMRO) effect in α-(BEDT-TTF) 2 MHg(SCN) 4 [M: K, NH 4 ] has been studied as a function of the polar and azimuthal angles of applied magnetic field with respect to the most conducting a c -plane. The ADMRO effects in these two structurally similar compounds are drastically different in their azimuthal angle dependence and oscillation waveform. While the ADMRO in NH 4 Hg-salt is of the standard type arising from a warped cylindrical Fermi surface, that in KHg-salt is a novel type to be attributed to an open Fermi sheet. Calculation based on a model recently proposed for a quasi one-dimensional system quantitatively reproduces the essential features of the anomalous ADMRO in KHg-salt.