title: Collective Modes and Structural Modulation in Ni-Mn-Ga(Co) Martensite Thin Films Probed by Femtosecond Spectroscopy and Scanning Tunneling Microscopy.
abstract: The origin of the martensitic transition in the magnetic shape memory alloy Ni-Mn-Ga has been widely discussed. While several studies suggest it is electronically driven, the adaptive martensite model reproduced the peculiar nonharmonic lattice modulation. We used femtosecond spectroscopy to probe the temperature and doping dependence of collective modes, and scanning tunneling microscopy revealed the corresponding static modulations. We show that the martensitic phase can be described by a complex charge-density wave tuned by magnetic ordering and strong electron-lattice coupling.
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors: M
authors: M
authors: Schubert
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.|Institute of Physics, Ilmenau University of Technology, 98693 Ilmenau, Germany.
authors: H
authors: H
authors: Schaefer
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors: J
authors: J
authors: Mayer
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors: A
authors: A
authors: Laptev
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors: M
authors: M
authors: Hettich
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors: M
authors: M
authors: Merklein
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors: C
authors: C
authors: He
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors: C
authors: C
authors: Rummel
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors: O
authors: O
authors: Ristow
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors: M
authors: M
authors: Großmann
authors: I. Physikalisches Institut, Georg-August-Universität Göttingen, 37073 Göttingen, Germany.
authors: Y
authors: Y
authors: Luo
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.|Laboratoire d'Acoustique, LAUM, UMR CNRS 6613, LUNAM Université, Université du Maine, 72085 Le Mans, France.
authors: V
authors: V
authors: Gusev
authors: I. Physikalisches Institut, Georg-August-Universität Göttingen, 37073 Göttingen, Germany.
authors: K
authors: K
authors: Samwer
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors: M
authors: M
authors: Fonin
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors: T
authors: T
authors: Dekorsy
authors: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.|Institute of Physics, Ilmenau University of Technology, 98693 Ilmenau, Germany.|Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany.
authors: J
authors: J
authors: Demsar