High-pressure study of the non-Fermi liquid material U 2 Pt 2 In

Abstract

The effect of hydrostatic pressure (p ≤ 1.8 GPa) on the non-Fermi liquid state of U 2 Pt 2 In 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 2 Pt 2 In 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 2 Pd 2 In. A simple Doniach-type diagram for U 2 Pt 2 In and U 2 Pd 2 In under pressure is presented.

How do Fermi liquids get heavy and die?

“…at the quantum critical point of these three dimensional materials. Further support for this conclusion is provided by the observation that the quadratic coefficient A of the resistivity grows in the approach to the quantum critical point [22]. As yet however, surprisingly little is known about the variation of the zero-temperature linear specific heat coefficient in the approach to the quantum critical point.…”

“…(See table 1.) Two stoichiometric heavy fermion systems, CeNi 2 Ge 2[16], U 2 P t 2 In[22] lie almost at a quantum critical point at ambient pressure, whilst the compounds CeCu 6[13,21] and Y bRh 2 Si 2[20] can be tuned to a quantum critical point with a tiny amount of chemical pressure, applied by doping. There is a growing list of antiferromagnetic cerium and uranium systems that can be driven paramagnetic by the application of pressure, including CeP d 2…”

Local fluctuations in quantum critical metals

“…While the extent to which an underlying quantum critical point (QCP) plays a role in the non-Fermi-liquid behavior of high-temperature superconductors remains a subject of debate, 4 the situation is much clearer in heavy-fermion metals. Among the many heavy-fermion materials in which non-Fermi-liquid properties have been seen, 1,[5][6][7][8][9][10][11][12][13][14][15] magnetic QCPs have been explicitly identified in a number of stoichiometric or nearly stoichiometric materials [5][6][7][8] including CeCu 6−x Au x , CePd 2 Si 2 , CeIn 3 , and YbRh 2 Si 2 . In each of these systems, the zerotemperature magnetic ordering transition appears to be continuous.…”

Quantum phase transitions

“…All of these systems are "dirty" in the sense that Ap <C po in the temperature range where the above exponents have been fitted. Also, resistivity measurements experiments in U2Pt2ln and UsNisSiM [86,87] have been fitted to the theory. In the cleanest samples the resistivity is almost linear in T over a substantial temperature range.…”