Ultrafast Structural Dynamics along the beta - gamma Phase Transition Path in MnAs

Vidal, FranckZheng, YunlinLounis, LounesCoelho, LeticiaLaulhe, ClaireSpezzani, CarloCiavardini, AlessandraPopescu, HoriaFerrari, EugenioAllaria, EnricoMa, JialinWang, HailongZhao, JianhuaChollet, MatthieuSeaberg, MatthewAlonso-Mori, RobertoGlownia, James M.Eddrief, MahmoudSacchi, Maurizio2019-06-182019-06-182019-06-182019-04-0910.1103/PhysRevLett.122.145702https://infoscience.epfl.ch/handle/20.500.14299/158084WOS:000463902800013We investigate the orthorhombic distortion and the structural dynamics of epitaxial MnAs layers on GaAs(001) using static and time-resolved x-ray diffraction. Laser-induced intensity oscillations of Bragg reflections allow us to identify the optical phonon associated with orthorhombic distortion and to follow its softening along the path towards an undistorted phase of hexagonal symmetry. The frequency of this mode falls in the THz range, in agreement with recent calculations. Incomplete softening suggests that the beta - gamma transformation deviates from a purely second-order displacive transition.Physics, MultidisciplinaryPhysicsmagnetic-propertiesmagnetoresistancedisorderUltrafast Structural Dynamics along the beta - gamma Phase Transition Path in MnAstext::journal::journal article::research article