ESR study of the spin ladder with uniform Dzyaloshinskii-Moriya interaction

Abstract

Evolution of the ESR absorption in a strong-leg spin ladder magnet (C7H10N2)2CuBr4 (abbreviated as DIMPY) is studied from 300 K to 400 mK. Temperature dependence of the ESR relaxation follows a staircase of crossovers between different relaxation regimes. We ague that the main mechanism of ESR line broadening in DIMPY is uniform Dzyaloshinskii-Moria interaction (|D| = 0.20 K) with an effective longitudinal component along an exchange bond of Cu ions within the legs resulting from the low crystal symmetry of DIMPY and nontrivial orbital ordering. The same DzyaloshinskiiMoriya interaction results in the lifting of the triplet excitation degeneracy, revealed through the weak splitting of the ESR absorption at low temperatures.

Hierarchy of Exchange Interactions in the Triangular-Lattice Spin Liquid YbMgGaO4

“…Their detection, however, remains a central challenge for condensed matter physics [6], and relies on the presence of quantum entanglement in their ground state and fractional quasiparticles in their excitation spectra. While the former can be checked by numerics [7], the latter can be experimentally detected by thermodynamic techniques [8][9][10] or spectroscopic probes such as inelastic neutron scattering [11][12][13][14][15][16][17] and electronspin resonance [18][19][20][21].…”

Electron spin resonance study of spin relaxation in the strong-leg spin ladder with nonmagnetic dilution

“…A. Reference results for pure DIMPY ESR in pure DIMPY was reported in details earlier [17,18]. Examples of ESR absorption spectra are shown in the left panel of Fig.…”

“…Analysis of the high-temperature ESR linewidth in pure DIMPY [17] proved that the DM interaction is the main relaxation mechanism in DIMPY. This anal- Sample orientation corresponds to maximum of ESR component splitting (H (X+Y)).…”

“…Thus, there are two equivalent spin ladders, which are differently oriented with respect to the crystal. Due to the g-factor anisotropy ESR responses of different ladders can be resolved, maximal separation of the absorption signals was observed for H||(X + Y), here X, Y are the unit vectors parallel to the a and b directions correspondingly [17].…”

“…Consistency of description of DIMPY by the spin ladder model was proved by the neutron scattering measurements, the values of exchange couplings and the gap were determined from the inelastic neutron scattering experiment: J leg =1.42 meV, J rung =0.82 meV and ∆=0.33 meV [16]. Besides of the Heisenberg exchange coupling in pure DIMPY (x = 0%) ESR spectroscopy revealed presence of the uniform Dzyaloshinskii-Moriya (DM) interaction D=0.03 meV [17,18].…”