Regensburg 2016 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 48: Poster Session II

MA 48.55: Poster

Donnerstag, 10. März 2016, 15:00–18:00, Poster B1

Critical Point in Antiferromagnetic Chromium Under Uniaxial Pressure — •Alexander Schade, Robert Georgii, Tim Adams, Alfonso Chacon, and Peter Böni — Technische Universität München

The weakly first order character of the Néel transition in chromium has not yet been conclusively explained. Chromium exhibits an incommensurable spin density wave, which is stabilized by the nesting of its Fermi surface. Zvi Barak et al. [1] interpret the Néel transition of chromium as fluctuation induced first order transition, and predict the existence of a critical point in a temperature over uniaxial pressure phase diagram for pressure along the 110-direction. We report elastic neutron scattering experiments with uniaxial pressure along the 110-axis, performed at MIRA, MLZ [2]. The Néel transition remains first order for pressures up to 600 bar. For higher pressures, an irreversible broadening of the Néel transition was observed, which we show is compatible with a model of plastic deformation, leaving behind residual stresses. The existence of a critical point can be ruled out in the pressure range 0-600 bar.

[1] Effect of uniaxial stress on the first-order Neel transition in chromium, Zvi Barak and M. B. Walker, J. Phys. F: Met. Phys., 12(1982)483-95.

[2] MIRA: Dual wavelength band instrument, Robert Georgii, Klaus Seemann, Journal of large-scale research facilities JLSRF, Vol 1 (2015)