Europhys. Lett.
Volume 72, Number 3, November 2005
Page(s) 479 - 485
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 30 September 2005
Europhys. Lett., 72 (3), pp. 479-485 (2005)
DOI: 10.1209/epl/i2005-10249-1

From ferro- to antiferromagnetism via exchange-striction of $\chem{MnAs/GaAs(001)}$

H. Yamaguchi, A. K. Das, A. Ney, T. Hesjedal, C. Pampuch, D. M. Schaadt and R. Koch

Paul-Drude-Institut für Festkörperelektronik - Hausvogteiplatz 5-7 D-10117 Berlin, Germany

received 22 July 2005; accepted in final form 8 September 2005
published online 30 September 2005

We investigated the stress evolution in single-crystal $\chem{MnAs}$ films on $\chem{GaAs(001)}$ upon applying high external magnetic fields in the $\alpha/\beta$ phase transition regime (10-40 $^{\circ}$C) and beyond. Our stress measurements reveal large field-induced lattice distortions at temperatures, where $\beta$- $\chem{MnAs}$ is present, even well above the phase transition ( $>40\,^{\circ}$C). A quantitative comparison with the field-induced increase of magnetization reveals that the changes in the lattice dimensions can be fully explained by the (reversible) back-transformation of $\beta$- $\chem{MnAs}$ to $\alpha$- $\chem{MnAs}$. Our direction-dependent experiments identify the structural distortions at the phase transition as a volume magnetostriction effect and -due to the persisting magnetocrystalline anisotropy above $40\,^{\circ}$C- strongly support an antiferromagnetic state for $\beta$- $\chem{MnAs.}$

75.70.Ak - Magnetic properties of monolayers and thin films.
68.60.Bs - Mechanical and acoustical properties.
75.80.+q - Magnetomechanical and magnetoelectric effects, magnetostriction.

© EDP Sciences 2005