Quantum oscillations in the linear chain of coupled orbits: The organic metal with two cation layers θ-(ET) ₄ CoBr ₄ (C ₆ H ₄ Cl ₂ )

Abstract

Analytical formulae for de Haas-van Alphen (dHvA) oscillations in linear\nchain of coupled two-dimensional (2D) orbits (Pippard's model) are derived\nsystematically taking into account the chemical potential oscillations in\nmagnetic field. Although corrective terms are observed, basic (alpha) and\nmagnetic breakdown-induced (beta and 2beta - alpha) orbits can be accounted for\nby the Lifshits-Kosevich (LK) and Falicov-Stachowiak semiclassical models in\nthe explored field and temperature ranges. In contrast, the 'forbidden orbit'\nbeta - alpha amplitude is described by a non-LK equation involving a product of\ntwo classical orbit amplitudes. Furthermore, strongly non-monotonic field and\ntemperature dependence may be observed for the second harmonics of basic\nfrequencies such as 2alpha and the magnetic breakdown orbit beta + alpha,\ndepending on the value of the spin damping factors. These features are in\nagreement with the dHvA oscillation spectra of the strongly 2D organic metal\ntheta- theta-(ET)(4)CoBr(4)(C(6)H(4)Cl(2)).\n