Temperature Dependence of Crystal Structures and Band Parameters in Quantum Spin Liquid β′-EtMe3Sb[Pd(dmit)2]2 and Related Materials

Abstract

Abstract:In an isostructural series of anion radical salts β -(Me 4-x Et x Z)[Pd(dmit) 2 ] 2 (Z = P, As, Sb;− units form a two-dimensional Mott insulator layer with a quasi-isosceles triangular lattice. The anisotropy of the triangular lattice is characterized by a ratio of interdimer transfer integrals, t /t. The crystal structures of EtMe 3 Sb, Me 4 Sb, Me 4 As, and Et 2 Me 2 As salts were determined in the range of 5-295 K by the single crystal X-ray diffraction technique. Interdimer transfer integrals, Fermi surface, and band structures at low temperatures were calculated by the tight binding method and the first-principles density-functional theory (DFT) method based on experimentally obtained crystal structures. Interdimer transfer integrals increased with lowering temperature. At 5 K, the ratio t /t decreased by about 15% from the room temperature value in every salt. The relationship between the transfer integrals and interdimer S· · · S distances indicated that the change of the t /t value with temperature was due to a thermal contraction, rather than the arch-shaped molecular distortion of the Pd(dmit) 2 molecule associated with the cation dependence of t /t.

A Discrepancy in Thermal Conductivity Measurement Data of Quantum Spin Liquid β′-EtMe3Sb[Pd(dmit)2]2 (dmit = 1,3-Dithiol-2-thione-4,5-dithiolate)

“…In both cases, the space group remained C2/c and no additional diffraction peak was observed. Determined crystal structures were identical with the previous result [23], and did not show any significant effects of the cooling rate on temperature factors and differential Fourier synthesis (Table 1). In the crystal, the EtMe 3 Sb + cation is located on the 2-fold axis (//b).…”

Transition of a pristine Mott insulator to a correlated Fermi liquid: Pressure-dependent optical investigations of a quantum spin liquid

“…The quasi-two-dimensional electronic properties stem from the conduction band formed by the dominant p-orbital of the sulphur atom in [Pd(dmit) 2 ] 2 . The bands of EtMe 3 Sb are well below the Fermi level [15][16][17] .…”

Electronic correlation and geometrical frustration in molecular solids: A systematic ab initio study of β′−X[Pd(dmit)2]2Misawa1, Yoshimi2, Tsumuraya3 2020Phys. Rev. ResearchSelf Cite14280View full textAdd to dashboardCite

“…To derive low-energy effective Hamiltonians, we first perform non-spin-polarized calculations with a first-principles DFT method [30,31] and obtain the Bloch functions for the experimental structures of the nine members of β -type X [Pd(dmit) 2 ] 2 , whose structures are measured above the antiferromagnetic or charge ordering transition temperature [32,33]. All the structures have the same space group symmetry of C2/c.…”