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Colóquios 2016


Colóquio: The effect of magnetic fields on a spin inter-orbital density wave.S.Magalhães
23.08.2016 16.00 h
Anfiteatro Antônio Cabral - Porto Alegre
Colóquios 2016


The effect of magnetic fields on a spin inter-orbital density wave


The nature of the Hidden Order state present in the heavy-fermion compound URu2Si2 remains a longstanding unsolved puzzle. Quite recently, the spin-rotationally invariant form of the underscreened Anderson lattice model has been proposed as describing the Hidden Order phase transition in URu2Si2. The spontaneous symmetry breaking found in the model has lead to a new concept; a spin inter-orbital density wave (SIDW) [1]. Here we report results for the SIDW focusing on the effects of the magnetic field. For instance, our results show that the magnetic susceptibility is very dependent on the orientation of the field. Moreover, the susceptibility decreases abruptly as the temperature is lowered below the phase transition temperature THO. These results are in agreement with experimental findings [2,3] and, in particular, they can account for the magnetic nematicity reported by Okazaki [3]. We also obtain the phase diagram for magnetic fields parallel to the easy-axis. It shows that the second-order phase transition is replaced by a first-order one above a critical value of the magnetic field. Further increase of the magnetic field leads to a quantum critical end point. We present results for the specific heat C(T), which display a gradual sharpening of the C(T) anomaly as the magnetic field is increased. The results are consistent with previous experimental findings [4]. Finally, we discuss the conditions and the nature of a direct phase transition between the SIDW and antiferromagnetic phases which occurs, in the absence of a magnetic field, when the hybridization is varied.

[1] Peter S. Riseborough, B. Coqblin, S. G. Magalhaes, Phys. Rev. B, 85, 165116 (2013).

[2] M. B. Maple et al., Phys. Rev. Lett., 56, 185 (1986).

[3] R. Okazaki et al., Science, 331, 439 (2011).

[4] V. F. Correa et al., Phys. Rev. Lett., 109, 246405 (2012). M. Jaime et al., Phys. Rev. Lett., 89, 287201 (2002).


Anfiteatro Antônio Cabral
Porto Alegre
Rio Grande do Sul
País: br


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Terça, Dezembro 07, 2021