Quantum Spin Effect and Short-Range Order above the Curie Temperature

TL;DR

This paper demonstrates that quantum spin effects significantly influence magnetic short-range order and spin-wave excitations above the Curie temperature, challenging traditional views on finite temperature magnetism.

Contribution

It introduces a generalized Green's function approach for arbitrary spins to analyze quantum effects on magnetic properties above the Curie point.

Findings

Quantum effects enhance short-range magnetic order.

Propagating spin-wave excitations persist above Curie temperature.

Quantum considerations are crucial for understanding finite temperature magnetism.

Abstract

Using quantum Heisenberg model calculations with Green's function technique generalized for arbitrary spins, we found that for a system of small spins the quantum spin effects significantly contribute to the magnetic short-range order and strongly affect physical properties of magnets. The spin dynamics investigation confirms that these quantum spin effects favor the persistence of propagating spin-wave excitations above the Curie temperature. Our investigation suggests a reconsideration of prevailing point of view on finite temperature magnetism to include quantum effects and the magnetic short-range order.