In this work we present a study of the low temperature magnetic phases of polycrystalline MnCr2O4 spinel through dc magnetization and ferromagnetic resonance spectroscopy (FMR). Through these experiments we determined the main characteristic temperatures: TC∼41 K and TH∼18 K corresponding, respectively, to the ferrimagnetic order and to the low temperature helicoidal transitions. The temperature evolution of the system is described by a phenomenological approach that considers the different terms that contribute to the free energy density. Below the Curie temperature the FMR spectra were modeled by a cubic magnetocrystalline anisotropy to the second order, with K1 and K2 anisotropy constants that define the easy magnetization axis along the <110> direction. At lower temperatures, the formation of a helicoidal phase was considered by including uniaxial anisotropy axis along the [1-10] propagation direction of the spiral arrange, with a Ku anisotropy constant. The values obtained from the fittings at 5 K are K1=-2.3x104 erg/cm3, K2=6.4x104 erg/cm3 and Ku=7.5x104 erg/cm3.
@article{arxiv.1411.2461,
title = {Temperature evolution of the effective magnetic anisotropy in the MnCr$_2$O$_4$ spinel},
author = {Dina Tobia and Julián Milano and María Teresa Causa and Elin L. Winkler},
journal= {arXiv preprint arXiv:1411.2461},
year = {2014}
}