Journal of Physical Studies 5(3/4), 355–368 (2001)
DOI: https://doi.org/10.30970/jps.05.355

LINEAR AND CUBIC DYNAMIC SUSCEPTIBILITIES IN QUANTUM SPIN GLASS

G. Busiello1, R. V. Saburova2, V. G. Sushkova2

1Dipartimento di Fisica ‟E.R. Caianiello”, Università di Salerno,
84081 Baronissi–Salerno and INFM — Unità di Salerno, Salerno, Italy.
0usiello@sa.infn.it 2Department of Physics, Kazan State Power-Engineering University,
Krasnoselskaya Str. 51, Kazan, 420066 Russia.

The low temperature behaviour of the dynamic nonlinear (cubic) susceptibility $ χ'_{3}(ω, T)$ in quantum $d$-dimensional Ising spin glass with short-range interactions between spins is investigated in terms of the quantum droplet model and the quantum-mechanical nonlinear response theory is employed. We have revealed a glassy like behaviour of droplet dynamics. The frequency dependence of $ χ'_{3}(ω, T)$ is very remarkable, the temperature dependence is found at very low temperatures (quantum regime). The nonlinear response depends on the tunneling rate for a droplet which regulates the strength of quantum fluctuations. This response has a strong dependence on the distribution of droplet free energies and on the droplet length scale average. Implications for experiments in quantum spin glasses like disordered dipolar quantum Ising magnet ${\rm LiHo}_x{\rm Y}_{1-x}{\rm F}_4$ and pseudospin are noted.

PACS number(s): 75.40.Gb, 75.10.Nr, 64.70.Pf

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