Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 38: Magnetic Materials II
MA 38.9: Vortrag
Donnerstag, 3. April 2014, 11:45–12:00, HSZ 403
Low temperature scanning tunneling microscopy of the Ni2MnGa(001) surface. — •Niklaus Blenk1, Aleksej Laptev1, Mikhail Fonin1, S. W. D’Souza2, and Sudipta Roy Barman2 — 1Fachbereich Physik, Universität Konstanz, 78457 Konstanz — 2UGC-DAE Consortium for Scientific Research, 452001 Indore, India
Due to their possible applications as actuators and sensors ferromagnetic shape memory alloys (FSMA) have attracted strong scientific interest. Ni-Mn-Ga is the most prominent and the most studied FMSA due to demonstrated magnetic field induced strains of up to 12% [1].
Here we report on low temperature STM-measurements on the Ni2MnGa(001) surface performed at 10 K. At this temperature the Ni2MnGa single crystal is in the ferromagnetic state and shows a 5M modulated martensitic structure. We observe charge-density modulations with a wavelength of 1.4 nm and wavefronts aligned along the [010] direction associated with a bulk charge-density wave (CDW). The modulation period is shown to be independent on the tunneling voltage UT. On the other hand the resulting corrugation amplitude depends on UT. A phase shift in the modulation appears at around 100 mV.
The observed co-existence of ferromagnetism and a CDW in Ni2MnGa is in agreement with the observation of a pseudogap, which hallmarks the CDW, by photoemission techniques [2,3].
[1] A. Sozinov et al., Appl. Phys. Lett. 102, 021902 (2013).
[2] D’Souza et al., Phy. Rev. B 85, 085123 (2012).
[3] C. P. Opeil et al., Phys. Rev. Lett. 100, 165703 (2008).