2,173 research outputs found
High pressure transport study of non-Fermi liquid behaviour in U2Pt2In and U3Ni3Sn4
The strongly correlated metals U2Pt2In and U3Ni3Sn4 show pronounced non-Fermi
liquid (NFL) phenomena at ambient pressure. Here we review single-crystal
electrical resistivity measurements under pressure (p <= 1.8 GPa) conducted to
investigate the stability of the NFL phase. For tetragonal U2Pt2In (I||a) we
observe a rapid recovery of the Fermi-liquid T^2-term with pressure. The
Fermi-liquid temperature varies as T_FL ~ p-p_c, where p_c= 0 is a critical
pressure. The analysis within the magnetotransport theory of Rosch provides
evidence for the location of U2Pt2In at a zero pressure antiferromagnetic
quantum critical point (QCP). In the case of cubic U3Ni3Sn4 we find T_FL ~
(p-p_c)^1/2. The analysis provides evidence for an antiferromagnetic QCP in
U3Ni3Sn4 at a negative pressure p_c= -0.04+-0.04 GPa.Comment: 6 pages (4 figures); to appear in Proc. of Int. Conf. PPHMF-IV (20-25
Oct. 2001, Santa Fe
Ordered magnetic and quadrupolar states under hydrostatic pressure in orthorhombic PrCu2
We report magnetic susceptibility and electrical resistivity measurements on
single-crystalline PrCu2 under hydrostatic pressure, up to 2 GPa, which
pressure range covers the pressure-induced Van Vleck
paramagnet-to-antiferromagnet transition at 1.2 GPa. The measured anisotropy in
the susceptibility shows that in the pressure-induced magnetic state the
ordered 4f-moments lie in the ac-plane. We propose that remarkable pressure
effects on the susceptibility and resistivity are due to changes in the
quadrupolar state of O22 and/or O20 under pressure. We present a simple
analysis in terms of the singlet-singlet model.Comment: 14 pages, 9 figures submitted to Phys. Rev.
High-pressure study of the basal-plane anisotropy of the upper critical field of the topological superconductor SrxBi2Se3
We report a high-pressure transport study of the upper-critical field,
, of the topological superconductor SrBiSe ( K). was measured for magnetic fields directed along two
orthogonal directions, and , in the trigonal basal plane. While
superconductivity is rapidly suppressed at the critical pressure
GPa, the pronounced two-fold basal-plane anisotropy at K, recently reported at ambient pressure (Pan et al., 2016), is
reinforced and attains a value of at the highest pressure (2.2 GPa).
The data reveal that the unconventional superconducting state with broken
rotational symmetry is robust under pressure
Angular variation of the magnetoresistance of the superconducting ferromagnet UCoGe
We report a magnetoresistance study of the superconducting ferromagnet UCoGe.
The data, taken on single-crystalline samples, show a pronounced structure at
~T for a field applied along the ordered moment . Angle
dependent measurements reveal this field-induced phenomenon has an uniaxial
anisotropy. Magnetoresistance measurements under pressure show a rapid increase
of to 12.8~T at 1.0~GPa. We discuss in terms of a field induced
polarization change. Upper critical field measurements corroborate the unusual
S-shaped -curve for a field along the -axis of the orthorhombic
unit cell.Comment: 6 pages, 5 figures; accepted for publication in Phys. Rev.
Enhancement of superconductivity near the ferromagnetic quantum critical point in UCoGe
We report a high-pressure single crystal study of the superconducting
ferromagnet UCoGe. Ac-susceptibility and resistivity measurements under
pressures up to 2.2 GPa show ferromagnetism is smoothly depressed and vanishes
at a critical pressure GPa. Near the ferromagnetic critical point
superconductivity is enhanced. Upper-critical field measurements under pressure
show attains remarkably large values, which provides solid evidence
for spin-triplet superconductivity over the whole pressure range. The obtained
phase diagram reveals superconductivity is closely connected to a
ferromagnetic quantum critical point hidden under the superconducting `dome'.Comment: 4 pages, 3 figures; accepted for publication in PR
Superconductivity under pressure in the Dirac semimetal PdTe2
The Dirac semimetal PdTe was recently reported to be a type-I
superconductor (1.64 K, mT) with unusual
superconductivity of the surface sheath. We here report a high-pressure study,
GPa, of the superconducting phase diagram extracted from
ac-susceptibility and transport measurements on single crystalline samples.
shows a pronounced non-monotonous variation with a maximum 1.91 K around 0.91 GPa, followed by a gradual decrease to 1.27 K at 2.5 GPa.
The critical field of bulk superconductivity in the limit ,
, follows a similar trend and consequently the -curves
under pressure collapse on a single curve: .
Surface superconductivity is robust under pressure as demonstrated by the large
superconducting screening signal that persists for applied dc-fields . Surprisingly, for GPa the superconducting transition
temperature at the surface is larger than of the bulk. Therefore
surface superconductivity may possibly have a non-trivial nature and is
connected to the topological surface states detected by ARPES. We compare the
measured pressure variation of with recent results from band structure
calculations and discuss the importance of a Van Hove singularity.Comment: manuscript 9 pages with 8 figures + supplemental material 3 pages
with 6 figure
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.Comment: 21 pages (including 5 figures); pdf forma
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