Interplay between the d - and π -electron systems in magnetic torque of the layered organic conductor κ -(BETS) 2Mn

Abstract

In the organic charge transfer salt κ-(BETS) 2 Mn[N(CN) 2 ] 3 the metallic conductivity is provided by itinerant π-electrons in the layers of BETS molecules, whereas magnetization is largely dominated by the localized d-electrons of the Mn 2+ ions in the insulating anionic layers. We study magnetic properties of the compound in its low-temperature, Mott-insulating state by means of magnetic torque technique. The complex behavior of the torque can be qualitatively explained by the coexistence of two weakly interacting magnetic subsystems associated with paramagnetic d-electron spins and antiferromagnetically ordered π-electron spins, respectively. Based on the experimental data, we determine the principal axes of magnetization of the Mn 2+ sublattice and propose a qualitative model for the π-electron spin arrangement, implying an important role of the Dzyaloshinskii-Moriya interaction.

Spin Vortex Crystal Order in Organic Triangular Lattice Compound

“…Magnetic order in the BETS layer onsets at T N ∼ 22 K in conjunction with a metal-insulator transition (MIT). This transition is marked by a significant broadening of the 13 C NMR resonances [27,28] and the appearance of a field-induced spin reorientation detected via magnetic torque [26,29]. However, as we elaborate in this work, the angle-dependence of the torque and specific pattern of NMR resonances are incompatible with conventional collinear magnetic orders.…”

“…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.…”

“…However, as we elaborate in this work, the angle-dependence of the torque and specific pattern of NMR resonances are incompatible with conventional collinear magnetic orders. The precise magnetic structure of the BETS at ambient pressure, and the role of Mn S = 5/2 spins in the anion layer therefore remain open questions [26,29].…”

Fermi surface properties of the bifunctional organic metal κ−(BETS)2Mn[N(CN)2]Zverev1, Biberacher2, Oberbauer3 et al. 2019Phys. Rev. BSelf Cite8020View full textAdd to dashboardCite

“…Indeed, the magnetoresistance, especially in the interlayer direction, may be sensitive to the magnetic state of Mn 2+ ions in the anion layer. The ambient-pressure magnetic experiments [16][17][18] have revealed a dramatic slowing of the spin dynamics in the manganese subsystem at low temperatures and considerable interactions with antiferromagnetically ordering π -electron spins in the Mott-insulating state. However, at present we do not have enough data to establish a direct link between the magnetoresistance behavior and magnetic properties.…”

“…In the present material this coupling seems to be considerably weaker. It has been found to cause changes of magnetic properties of the Mn 2+ subsystem upon entering the insulating state [16][17][18]. However, no evidence of its influence on the conducting system has been reported so far.…”