Anomaly in Spin Excitation Spectrum of Double-Exchange Systems with Randomness

Abstract

Spin excitation spectrum of the double-exchange model is studied in the presence of randomness. Spin wave approximation in the ground state shows that the randomness significantly modifies the spectrum from the cosine-like one in the pure system to that with anomalies such as broadening, anti-crossing and gap opening. The origin of anomalies is speculated to be modulation of effective ferromagnetic coupling by the Friedel oscillation. These anomalies qualitatively reproduce the spin excitation spectrum in colossal magnetoresistance manganites whose Curie temperatures are relatively low. Our results suggest that randomness control is an important notion to understand effects of the A-site substitution which has previously been understood as the bandwidth control.

4 pages including 3 figures

References in corpus (2)

• Approach to the metal-insulator transition in La(1-x)CaxMnO3 (0<x<.2): magnetic inhomogeneity and spin wave anomaly
• Dynamical mean-field theory of a double-exchange model with diagonal disorder

Cited by in corpus (7)

• Competing Orders and Disorder-induced Insulator to Metal Transition in Manganites
• Monte Carlo Study of Doping Change and Disorder Effect on Double Exchange Ferromagnetism
• Magnons in Ferromagnetic Metallic Manganites
• Spectral Function Analysis on Spin Dynamics in Double-Exchange Systems with Randomness
• Colossal magnetoresistance and quenched disorder in manganese oxides
• Spin wave spectrum of a disordered double exchange model
• Perturbative calculation of the spin-wave dispersion in a disordered double-exchange model