Structure, magnetism, and magnetocaloric properties of MnFeP1−xSix compounds

MnFeP1-xSix compounds with x=0.10,0.20,0.24,0.28,...,0.80,1 were prepared by high-energy ball milling and solid-state reaction. The structural, magnetic, and magnetocaloric properties are investigated as a function of temperature and magnetic field. X-ray diffraction studies show that the samples in the range from x=0.28 to 0.64 adopt the hexagonal Fe2P-type structure with a small amount of second phase which increases with increasing Si content. The samples with lower Si content show the orthorhombic Co2P-type structure. Magnetic measurements show that the paramagnetic-ferromagnetic transition temperatures range from 214 to 377 K. Of much importance is the fact that these compounds do not contain any toxic components and exhibit excellent magnetocaloric properties

Evidence for a ferromagnetic quantum critical point in URhGe doped with Ru

We have investigated the evolution of ferromagnetic order in the correlated metal series URh_{1-x}Ru_{x}Ge. Magnetization, transport and specific heat measurements provide convincing evidence for a ferromagnetic quantum critical point at the critical concentration x_{c} = 0.38. Here we report ac-susceptibility and magnetization measurements on selected samples with Ru doping concentrations near the critical point.Comment: 2 pages, conference paper, submitted to the proceedings of SCES'0

Specific Heat, Susceptibility and High-Field Magnetisation Experiments on Heavy Fermion UPt3 Alloyed with Pd

Specific heat, susceptibility and high-field magnetisation experiments have been performed on a number of pseudobinary U(Pt1-xPdx)3 compounds with x ≤ 0.30. For low Pd concentrations (x ≤ 0.10) the spin-fluctuation contribution to the specific heat is enhanced with respect to pure UPt3. For x ≥ 0.15 the spin-fluctuation phenomena are lost. On alloying, the anomalies present for UPt3 in the susceptibility at 17 K and in the high-field magnetisation at 21 T (at 4.2 K), shift towards lower temperatures and fields, respectively, and have not been observed in a compound with x = 0.15. Superconductivity has not been found down to 40 mK in a U(Pt0.995Pd0.005)3 sample

Possible heavy-fermion behaviour of new U(Cu, Al)5 compounds

We have synthesized several new UCuxAl5 - x compounds in the composition range between x = 2.9 and x = 3.5, which were found to form in crystal structures related to the CaCu5 structure. Specific-heat measurements reveal a considerable enhancement of the low-temperature specific-heat coefficient γ for all U(Cu, Al)5 compounds investigated, with a maximum value of 450 mJ/molK2 at 1.2 K for UCu2.9Al2.1. © 1995.Acknowledgement: Work was supported by the "Sticht-ing voor Fundamenteel Onderzoek der Materie" (FOM)

Heat-capacity measurements on small samples: The hybrid method

A newly developed method is presented for measuring heat capacities on small samples, particularly where thermal isolation is not sufficient for the use of the traditional semiadiabatic heat-pulse technique. This "hybrid technique" is a modification of this heat-pulse method in case the temperature drift of the sample after the heat pulse is not linear but exponential. Deliberate extrapolations of these exponential drift curves, dependent on the evaluated relaxation time, yield reliable results for the temperature steps. The method is faster than the traditional relaxation method, and by comparing with the values published by the National Bureau of Standards (NBS) on copper, the accuracy is shown to be of the order of 1%

Magnetic phase diagrams of UNiGe

UNiGe undergoes two magnetic transitions in zero field. Here, the magnetic diagrams of UNiGe for B {parallel} b and B {parallel} c are reported. We performed temperatures scans of the magnetization in static magnetic fields up to 19.5T applied along the b and c axes. For both orientations 3 magnetic phases have been identified in the B-T diagrams. We confirmed the previously reported phase boundaries for B {parallel} c, and in addition we determined the location of the phase boundaries for B {parallel} b. We discuss a possible relationship of the two zero-field antiferromagnetic phases (commensurate: T<42K; incommensurate: 42K<T<50K) and the field-induced phase, which, at low temperatures, occurs between 18 and 25T or 4 and 10T for B {parallel} b or B {parallel} c, respectively. Finally, we discuss the field dependence of the electronic contribution {gamma} to the specific heat for B {parallel}c up to 17.5T, and we find that its field dependence is similar to the one found in more itinerant uranium compounds