Quantum spin effects and magnetic short-range order above the Curie temperature

TitleQuantum spin effects and magnetic short-range order above the Curie temperature
Publication TypeJournal Article
Year of Publication2009
AuthorsGu RY, Antropov VP
Journal TitlePhysical Review B
Date Published12/01
ISBN Number1098-0121
Accession NumberISI:000273228200050
Keywords', 2-dimensional heisenberg-model, bcc iron, curie temperature, d, ferromagnetic materials, green, green-function theory, heisenberg model, iron, itinerant ferromagnetism, local-band theory, s function methods, short-range order, spin dynamics, spin waves

Using the quantum Heisenberg model calculations with the Green's function technique generalized for arbitrary spins, we found that for a system of small spins, the quantum spin effects induce the additional magnetic short-range order and strongly affect physical properties of magnets. For instance, the spin waves in the present consideration can appear as a result of short-range spin fluctuations and do not require long-range magnetic order. Our spin dynamics investigation even indicates that these quantum spin effects favor the persistence of propagating spin-wave-like excitations above the Curie temperature. These model studies are relevant to itinerant magnets and suggest the increasing influence of quantum spin effects on the magnetic short-range order with a decrease in quantum spin value. The modified expression for the Curie temperature in ferromagnets is obtained.

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