Magnetic anisotropy of UCoGa

Abstract

Magnetization, ac and dc susceptibility of a UCoGa single crystal are presented. Magnetic ordering was detected below 47 K. The complicated magnetization behavior at low temperatures does not allow us to conclude unambiguously about the type of ground state. The observed strong uniaxial anisotropy is consistent with the behavior of other isostructural UTX compounds. The anisotropy field exceeds by far the highest field of 35 T applied in the experiments.

Effect of thermal history on magnetism in UCoGa

“…We can see that the lowest H c value was observed for the annealed sample SC2A900, whereas the as-grown SC2C shows the highest coercive field. The as-grown SC1A crystal exhibits an H c value comparable to that reported in literature [10]. When we inspect the temperature evolution of the magnetization curves an exponential decrease of H c with increasing temperature is found for all investigated crystals (Fig 2).…”

Extreme narrow magnetic domain walls in U ferromagnets: The UCoGa case

“…The inset of Fig. 4 shows a low-field detail of the hysteresis loop measured in field along the caxis field at 20 K. At this temperature, the coercive field is about 0.3 T. The coercivity collapses upon heating to temperatures above 26 K. This finding is in agreement with the results reported in Refs [20] and [29].…”

“…In this paper, we present the direct low-temperature investigation of a domain structure in a U 5felectron moment ferromagnet with TC << RT. UCoGa, a member of the family of UTX compounds with ZrNiAl-type of structure, has been selected as a typical U ferromagnet with huge uniaxial MA [20,[27][28][29][30] having the easy axis along the c-axis of the hexagonal structure. First, the UCoGa single a) b) crystal has been characterized by magnetization measurements in magnetic fields applied along the main crystallographic axes, a and c. The domain-structure imaging has been accomplished by using a low-temperature atomic force microscope -attoAFM/MFM Ixs (attocube).…”

Different universality classes of isostructural UTX compounds (T=Rh,Co,Opletal1, Sechovský2, Prokleška3 2020Phys. Rev. B

“…For stronger anisotropy, the region of 3D behavior is reduced. The large magnetocrystalline anisotropy observed in UTX compounds crystallizing in the ZrNiAl-type structure [8,11,15,39] observed as seen in URhGa, UCoGa and URhAl. It is important to emphasize that the systems described by Takahashi show different critical behaviors, but the effect of anisotropy on the nature of fluctuations near TC is expected to be similar.…”

“…To test this aspect we prepared single crystals of three hexagonal UTX ferromagnets -UCoGa [11,[13][14][15], URhGa [16][17][18] and UCo0.98Ru0.02Al (a close analog of UCo0.99Ru0.01Al [19,20]) and measured their magnetization isotherms in the neighborhood of their Curie temperature. The measured data were analyzed by investigating Arrott-Noakes plots [21,22], Kouvel-Fischer plots [23], critical isotherms, scaling theory [24] and Widom scaling relations [25] in order to determine the critical exponents and their corresponding universality classes.…”