Spin Dynamics of Double-Exchange Manganites with Magnetic Frustration

TL;DR

This paper investigates how magnetic frustration influences spin dynamics in double-exchange manganites, revealing charge-density wave formation, spin alignment effects, and phase separation, with implications for understanding experimental spin-wave stiffness jumps.

Contribution

It introduces a detailed analysis of magnetic frustration effects on spin dynamics in double-exchange models, highlighting charge-density wave formation and phase separation phenomena.

Findings

Charge-density wave forms with non-colinear local moments.

Increasing hopping energy aligns spins and increases spin-wave stiffness.

Phase separation occurs only within a narrow hopping energy range.

Abstract

This work examines the effects of magnetic frustration due to competing ferromagnetic and antiferromagnetic Heisenberg interactions on the spin dynamics of the double-exchange model. When the local moments are non-colinear, a charge-density wave forms because the electrons prefer to sit on lines of sites that are coupled ferromagnetically. With increasing hopping energy, the local spins become aligned and the average spin-wave stiffness increases. Phase separation is found only within a narrow range of hopping energies. Results of this work are applied to the field-induced jump in the spin-wave stiffness observed in the manganite Pr$_{1-x}$Ca$_x$MnO$_3$ with $0.3 \le x \le 0.4$.