Structural and Magnetic Dynamics in the Magnetic Shape Memory Alloy Ni${}_2$MnGa

Abstract

Magnetic shape memory Heusler alloys are multiferroics stabilized by the correlations between electronic, magnetic and structural order. To study these correlations we use time resolved x-ray diffraction and magneto-optical Kerr effect experiments to measure the laser induced dynamics in a Heusler alloy Ni${}_2$MnGa film and reveal a set of timescales intrinsic to the system. We observe a coherent phonon which we identify as the amplitudon of the modulated structure and an ultrafast phase transition leading to a quenching of the incommensurate modulation within 300~fs with a recovery time of a few ps. The thermally driven martensitic transition to the high temperature cubic phase proceeds via nucleation within a few ps and domain growth limited by the speed of sound. The demagnetization time is 320~fs, which is comparable to the quenching of the structural modulation.

arXiv comment5 pages, 3 figures. Supplementary materials 5 pages, 5 figures

References in corpus (6)

• First-principles study of lattice instabilities in the ferromagnetic martensite Ni${}_2$MnGa
• Combined experimental and theoretical investigation of the premartensitic transition in Ni${}_2$MnGa
• Observation of Phasons in Magnetic Shape Memory Alloy Ni2MnGa
• Modulated Martensite: Why it forms and why it deforms easily
• Insights into ultrafast demagnetization in pseudo-gap half metals
• Coherent phonon dynamics at the martensitic phase transition of Ni_2MnGa

Cited by in corpus (6)

• Modulations in martensitic Heusler alloys originate from nanotwin ordering
• Premartensite to martensite transition and its implications on the origin of modulation in Ni2MnGa ferromagnetic shape memory alloy
• Self-similar dynamics of order parameter fluctuations in pump-probe experiments
• Concepts and use cases for picosecond ultrasonics with x-rays
• Bulk Electronic Structure of Ni2MnGa studied by Density Functional Theory and Hard X-ray Photoelectron Spectroscopy
• Coupling between a charge density wave and magnetism in an Heusler material