- Petr Opletal: Quantum criticality of an itinerant 5f-electron ferromagnet: Ru doped UCoAl
- 4. 3. 2015, 14:50
- lecture room F2, first floor Ke Karlovu 5
- more information
Abstract:
UCoAl is an itinerant 5f-electron paramagnet appearing on the verge of ferromagnetism. At low temperatures it undergoes first-order metamagnetic phase transition (FOMPT) to ferromagnetic state with critical magnetic field Bc ~ 0.7 T applied along the c-axis and the critical temperature T0 = 11 K where FOMPT changes to crossover behavior. Bc (T0) increases (decreases) with applying hydrostatic pressure [1, 2]. FOMPT disappears at quantum critical endpoint at p = 1.5 GPa and B = 7 T [2]. This is in agreement with the generic (H,p,T) phase diagram for itinerant quantum ferromagnet [3]. Ferromagnetism in UCoAl can be induced by small amount of Ru substituted for Co [4]. We have grown single crystals of UCo1-xRuxAl for x = 0.0025, 0.005 and 0.01 and investigated their magnetic (H,p,T) phase diagram. Results of magnetic measurements and ongoing measurement of electrical resistivity, Hall Effect and thermal expansion will be presented. Evolution of magnetism in UCoAl and our single crystals within the generic (H,p,T) phase diagram of itinerant quantum ferromagnet will be discussed.
References:
1. Mushnikov, N.V., et al., Magnetic properties of the 5f itinerant electron metamagnet UCoAl under high pressure. Physical Review B, 1999. 59(10): p. 6877-6885.
2. Aoki, D., et al., Ferromagnetic Quantum Critical Endpoint in UCoAl. Journal of the Physical Society of Japan, 2011. 80(9).
3. Belitz, D., T.R. Kirkpatrick, and J. Rollbühler, Tricritical Behavior in Itinerant Quantum Ferromagnets. Physical Review Letters, 2005. 94(24): p. 247205.
4. Andreev, A.V., et al., Ferromagnetism in the UCo1-xRuxAl quasiternary intermetallics. Philosophical Magazine B-Physics of Condensed Matter Statistical Mechanics Electronic Optical and Magnetic Properties, 1997. 75(6): p. 827-844.