- Petr Opletal: URhGa single crystal and its behavior under hydrostatic pressure
- 9. 5. 2018, 14:30
- lecture room F2, first floor Ke Karlovu 5
- more information
Abstract:
In recent years ferromagnets proved to be interesting in regards to quantum criticality and quantum critical points due to the prediction of Belitz-Kirkpatrick-Vojta theory [1]. The BKV predicts four different possible phase diagrams depending on the level of disorder presented in material. In first phase diagram, for cleanest materials, 2nd order ferromagnetic phase transition is suppressed by change of tuning parameter until it reaches tricritical point (TCP), where it changes from 2nd order to the 1st one. Further tuning of parameter quickly suppresses 1st order transition. Additionally, metamagnetic transition appears at TCP in finite magnetic fields. Some of compounds exhibiting whole discontinuous phase diagram or part of it are ZrZn2 [2], UGe2 [3] and UCoAl [4].
Last compound belongs to family of UTX compounds (T – transition metal, X- p metal) and specifically to group, crystallizing in hexagonal ZrNiAl structure. Other compounds from this group were shown to exhibit discontinuous phase diagram (URhAl [5], UCoGa [6]), making this group interesting playground for exploration of discontinuous phase diagram. URhGa also crystallizes in hexagonal ZrNiAl structure and was reported to be ferromagnetic with TC = 44 K [7], making it a possible example of a compound exhibiting discontinuous phase diagram
We present our data obtained on single crystal of URhGa which we prepared. Magnetic, electric transport and heat capacity measurements were done in ambient and hydrostatic pressure. We compare our single crystal data with published results on polycrystalline samples. Phase diagram of URhGa will be discussed in comparison to phase diagrams of URhAl and UCoGa, which are closely related to URhGa.
[1] D. Belitz, et al., Physical Review Letters, 82 (1999).
[2] M. Uhlarz, et al., Physical Review Letters, 93 (2004).
[3] H. Kotegawa,et al., Journal of the Physical Society of Japan, 80 (2011).
[4] N. Kimura, et al., Physical Review B, 92 (2015).
[5] Y. Shimizu, et al., Physical Review B, 91 (2015).
[6] M. Míšek, et al., AIP Advances, 7 (2017).
[7] A.V. Andreyev, et al., Physics of Metals and Metallography, 62 (1986).