Fermi surface properties of the bifunctional organic metal κ−(BETS)2Mn[N(CN)2]

Abstract

We present detailed studies of the high-field magnetoresistance of the layered organic metal κ-(BETS) 2 Mn-[N(CN) 2 ] 3 under a pressure slightly above the insulator-metal transition. The experimental data are analyzed in terms of the Fermi surface properties and compared with the results of first-principles band structure calculations. The calculated size and shape of the in-plane Fermi surface are in very good agreement with those derived from Shubnikov-de Haas oscillations as well as the classical angle-dependent magnetoresistance oscillations. A comparison of the experimentally obtained effective cyclotron masses with the calculated band masses reveals electron correlations significantly dependent on the electron momentum. The momentum-or band-dependent mobility is also reflected in the behavior of the classical magnetoresistance anisotropy in a magnetic field parallel to layers. Other characteristics of the conducting system related to interlayer charge transfer and scattering mechanisms are discussed based on the experimental data. Besides the known high-field effects associated with the Fermi surface geometry, new pronounced features have been found in the angle-dependent magnetoresistance, which might be caused by coupling of the metallic charge transport to a magnetic instability in proximity to the metal-insulator phase boundary.

On the Size of Superconducting Islands on the Density-Wave Background in Organic Metals

“…Spatial phase segregation may also happen near the quantum critical point of the Mott-AFM metal-insulator phase transition, e.g., as observed in the κ-(BEDT-TTF) 2 X family of organic superconductors [69][70][71][72]. The observation of clear magnetic quantum oscillations [71,72] in the almost insulating phase of these materials indicates a rather large size d of metal/SC domains in the Mott insulator media, comparable to the electron cyclotron radius.…”

Ingredients for Generalized Models of κ-Phase Organic Charge-Transfer Salts: A Review

“…For comparison, in the compounds λ-(BETS) 2 FeCl 4 and κ-(BETS) 2 FeBr 4 , the Fe 3+ and organic spins order simultaneously [76][77][78]. Such features as Jaccarino-Peter superconductivity [79] and beats in the Shubnikov-de Haas effect, as reported in the latter compounds, are not observed in κ-Mn [24][25][26]. One example, where the experimental evidence of κ-Mn is not compatible with a 2SL or spiral order phase is the magnetic torque as a function of magnetic field [75].…”

“…As a result, a Mott insulator is expected to undergo an insulator-to-metal transition. This is indeed observed for various Mott-insulating κphase charge-transfer salts, including κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl [1,3,4,9,21,22] ('κ-Cl', Figure 3a) and κ-(BEDT-TTF) 2 Cu 2 (CN) 3 [5,7,23] ('κ-CuCN', Figure 3b) and κ-(BETS) 2 Mn [N(CN) 2 ] 3 ('κ-Mn') [24][25][26]. In all cases, very moderate pressures in the order of kbar, or even less, induce a Mott metal-insulator transition (MIT).…”

Spin Vortex Crystal Order in Organic Triangular Lattice Compound

“…For comparison, ∆S MIT is one order of magnitude smaller than the value observed for λ-(BETS) 2 FeX 4 (X = Cl, Br), where sizeable π-d interactions lead to simultaneous ordering of the Fe 3+ and π system [40,44,45]. In these λ-phase materials, π-d coupling also produces additional signatures that are absent in κ-Mn: (i) no field-induced Jaccarino-Peter superconductivity [25,26], and (ii) no beats in Shubnikov-de Haas effect [30]. We therefore conclude that the π-d coupling is sufficiently weak that the Mn spins play no significant role in the BETS magnetism.…”

“…In this letter, we consider the magnetic ground state of κ-(BETS) 2 Mn[N(CN) 2 ] 3 (κ-Mn) [22][23][24][25][26][27][28][29][30], which we demonstrate to lie in a parameter region conducive to chiral magnetic order. This material has a layered structure (Fig.…”