Reentrant hidden order at a metamagnetic quantum critical end point

Magnetization measurements of URu2Si2 in pulsed magnetic fields of 44 T reveal that the hidden order phase is destroyed before appearing in the form of a reentrant phase between approximately 36 and 39 T. Evidence for conventional itinerant electron metamagnetism at higher temperatures suggests that the reentrant phase is created in the vicinity of a quantum critical end point.     

Charge-density-wave transitions in the local-moment magnet Er5Ir4Si10

We report the observation of a new type of charge-density wave (CDW) in the large magnetic-moment rare-earth intermetallic compound, Er5Ir4Si10, which then orders magnetically at low temperatures. Single crystal x-ray diffraction shows the development of a 1D incommensurate CDW at 155 K, which then locks into a purely commensurate state below 55 K. The well-localized Er3+ moments are antiferromagnetically ordered below 2.8 K. We observe very sharp anomalies in the specific heat at 145 and 2.8 K, signifying the bulk nature of these transitions. Our data suggest the coexistence of strongly coupled CDW with local-moment antiferromagnetism in Er5Ir4Si10.     

Magnetism in UNi2Ga3

We present the physical properties of the new intermetallic compound UNi₂Ga₃. This compound crystallizes in the hexagonal CaCu₅-structure, and bulk experiments (specific heat c _p, susceptibility X, magnetization M and resistivity ρ) indicate the system to undergo a magnetic transition at 9.5 K. No superconductivity is observed down to 50 mK. The magnetic transition in UNi₂Ga₃ closely resembles that of the incommensurably ordered state in the related heavy-fermion superconductor UNi₂Al₃. In addition, and independently from the conditions for sample preparation, we found indications for a considerable degree of lattice disorder, likely due to structural Ga/Ni disorder. We discuss our results, particularly the absence of superconductivity in UNi₂Ga₃, in comparison to UNi₂Al₃.     

Interplay between fermi surface topology and ordering in URu2Si2 revealed through abrupt hall coefficient changes in strong magnetic fields

Temperature- and field-dependent measurements of the Hall effect of pure and 4% Rh-doped URu2Si2 reveal low density (0.03 hole/U) high mobility carriers to be unique to the "hidden order" phase and consistent with an itinerant density-wave order parameter. The Fermi surface undergoes a series of abrupt changes as the magnetic field is increased. When combined with existing de Haas-van Alphen data, the Hall data expose a strong interplay between the stability of the "hidden order," the degree of polarization of the Fermi liquid, and the Fermi surface topology.     

Resistivity minima in quench-condensed films of palladium

We have found a shallow low temperature minimum in the electrical resistivity of thin quench-condensed Pd-films. The depth and temperature of this minimum depends upon the residual resistivity of the film.     

Atomic short-range order and its relation to the magnetic behavior of noble-metal based spin-glass alloys

We have investigated the spatial distribution of magnetic atoms (Mn or Fe) by determining the short range order parameters for the archetypal spin-glass alloys: $\text{Cu}$Mn, $\text{Au}$Mn, $\text{Au}$Fe and $\text{Pt}$Mn in the dilute limit. All four systems possess atomic short-range order (ASRO) such as to enhance local ferromagnetic regions. In the latter three systems the ASRO is relatively strong and initiates long-range structures which develop with increasing concentration and which eventually destroy the spin-glass state.     

Thermopower of concentrated AuCr alloys

Measurements are presented of the thermopower of three concentrated $\text{Au}$Cr (0.9, 4.9 and 10.6 at.%Cr) alloys between 4 and 500°K. Considerable differences are observed in the thermopower compared with $\text{Au}$Fe alloys in a similar concentration range. Possible reasons for these differences are discussed in terms of current ideas on spin glasses and the pair model of Matho and Béal-Monod.     

Electrical resistivity and initial susceptibility of weakly ferromagnetic VFe alloys

Electrical resistivity measurements between 1.5 and 300°K on VFe alloys indicate that the large magnetic clusters in these alloys are stable up to 300°K. The onset of ferromagnetic ordering causes a sharp peak in the initial susceptibility and a clear kink in the temperature coefficient of resistivity, d?/dT.