arXiv subjects

F. R. de Boer

Publications and source records attributed to F. R. de Boer.

6 recordsLinked to original sources

arXiv2020

Magnetic phase diagram of the antiferromagnet U2Rh2Pb

A new U-based compound of the U2Rh2Pb, a new compound of the U2T2X series was prepared in a single-crystal form. Its structure was determined as belonging to the tetragonal Mo2FeB2 structure type with the shortest U-U spacing along the c. U2Rh2Pb undergoes an antiferromagnetic transition at TN of 20 K and exhibits an enhanced Sommerfeld coefficient 150 mJ/molK2. In contrast to the two rhodium analogues U2Rh2In and U2Rh2Sn, the easy-magnetization direction is the c with rather low value of the critical field 4.3 T of the metamagnetic transition of a spin-flip type. The observed dependences of TN and Hc on temperature and magnetic field have been used for constructing a magnetic phase diagram. The experimental observations are mostly supported by first-principles calculations.

cond-mat.str-el↗

arXiv2001

Extraordinary magnetization behavior of single crystalline TbFe_4.4Al_7.6

We report the observation of a field-induced transformation from the easy-plane antiferromagnetic structure to the easy-axis ferrimagnetic structure in a single crystal of TbFe_4.4Al_7.6 (tetragonal ThMn_12 structure) at 5 K. Such a field-induced, irreversible transition has been identified for the first time. This transition is accompanied by a giant orthorhombic distortion: epsilon_aa = - epsilon_bb ~ 3.5x10^-4 that is associated with a magnetic hardness (mu_0H_C ~ 3 T) that is unprecedented in this category of materials.

cond-mat.mtrl-sci↗

arXiv2001

Pressure-induced recovery of the Fermi-liquid state in the non-Fermi liquid material U2Pt2In

In the study of non-Fermi-liquid (NFL) phenomena in correlated metals, U2Pt2In is of special interest as it is one of the rare stoichiometric (undoped) materials that show NFL behaviour at ambient pressure. Here we report on the stability of the NFL phase with respect to hydrostatic pressure (p< 1.8 GPa). Electrical resistivity data under pressure, taken on a single-crystalline sample for a current in the tetragonal plane, show that T_FL, i.e. the temperature below which the Fermi-liquid T^2-term is observed, increases with pressure as T_FL ~ (p-p_c), where p_c~0 is a critical pressure. This provides strong evidence for the location of U2Pt2In at an antiferromagnetic quantum critical point.

cond-mat.str-el↗

arXiv2000

Recovery of the Fermi-liquid state in U_3Ni_3Sn_4 by pressure

Measurements of the resistivity of single-crystalline U_3Ni_3Sn_4 under hydrostatic pressure up to 1.8 GPa are reported. We show that the temperature T_FL, below which the resistivity obeys the Fermi-liquid expression rho ~ T^2, increases with pressure as T_FL ~ (p-p_c)^1/2. The analysis of the data within the magnetotransport theory of Rosch lends strong support for an antiferromagnetic quantum critical point in U_3Ni_3Sn_4 at a negative critical pressure p_c of -0.04+-0.02 GPa. The proximity to an antiferromagnetic instability in U_3Ni_3Sn_4 is consistent with the previously reported non-Fermi liquid term in the low-temperature specific heat.

cond-mat.str-el↗

arXiv2000

High-pressure study of the non-Fermi liquid material U_2Pt_2In

The effect of hydrostatic pressure (p<= 1.8 GPa) on the non-Fermi liquid state of U_2Pt_2In is investigated by electrical resistivity measurements in the temperature interval 0.3-300 K. The experiments were carried out on single-crystals with the current along (I||c) and perpendicular (I||a) to the tetragonal axis. The pressure effect is strongly current-direction dependent. For I||a we observe a rapid recovery of the Fermi-liquid T^2-term with pressure. The low-temperature resistivity can be analysed satisfactorily within the magnetotransport theory of Rosch, which provides strong evidence for the location of U_2Pt_2In at an antiferromagnetic quantum critical point. For I||c the resistivity increases under pressure, indicating the enhancement of an additional scattering mechanism. In addition, we have measured the pressure dependence of the antiferromagnetic ordering temperature (T_N= 37.6 K) of the related compound U_2Pd_2In. A simple Doniach-type diagram for U_2Pt_2In and U_2Pd_2In under pressure is presented.

cond-mat.str-el↗

arXiv1999

Resistivity of non-Fermi liquid U2Pt2In under pressure

Non-Fermi liquid behaviour in single-crystalline U2Pt2In has been studied by means of resistivity experiments (I||c) under hydrostatic pressure (P<1.5 GPa). At ambient pressure the resistivity rho(T) follows a power law rho~T^alpha with alpha~0.5. Upon applying pressure alpha increases. For P>1 GPa a minimum develops in rho(T). A study of the field dependence of the minimum confirms its magnetic origin. The ratio c/a is proposed as the effective control parameter, rather than the unit cell volume.

cond-mat.str-el↗