Anisotropy of the upper critical field near Tc and the properties of URu2Si2 and UBe13 in the normal state

Aliev, F. G.; Kovachik, V.; Moshchalkov, Victor; Pryadun, V.V.; Alekseevskiǐ, N. E.; Mitin, A. V.; Agraı̈t, Nicolás; Vieira, S.; Villar, R.

doi:10.1007/bf00682192

Cited by 32 publications

(28 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…E itself appears to also undergo an increase of a much smaller magnitude than ph , consistent with the claim that the electronic mean free path increases at the transition [18]. Note that the magnitude and T dependence of L XY XY =T XY at 2 T (and by implication, L) are very different from previous reports [8,9]. We make the general observation that indiscriminate use of the Lorenz ratio L = T using the raw ph E data should be thoughtfully reexamined.…”

Section: Fig 2 (Color Online) (A)supporting

confidence: 79%

See 1 more Smart Citation

Phonon Thermal Transport ofURu2Si2: Broken Translational Symmetry and Strong-Coupling of the “Hidden Order” to the Lattice

Sharma

Harrison²,

Jaime³

et al. 2006

Phys. Rev. Lett.

View full text Add to dashboard Cite

A dramatic increase in the total thermal conductivity ( ) is observed in the hidden order (HO) state of single crystal URu 2 Si 2 . Through measurements of the thermal Hall conductivity, we explicitly show that the electronic contribution to is extremely small, so that this large increase in is dominated by phonon conduction. An itinerant BCS or mean-field model describes this behavior well: the increase in is associated with the opening of a large energy gap at the Fermi surface, thereby decreasing electronphonon scattering. Our analysis implies that the ''hidden order'' parameter is strongly coupled to the lattice, suggestive of a broken symmetry involving charge degrees of freedom. DOI: 10.1103/PhysRevLett.97.156401 PACS numbers: 71.27.+a, 71.28.+d, 72.15.Eb At symmetry breaking (2nd order) phase transitions, an ''order parameter'' must characterize the nonsymmetric, low temperature state [1]. The heavy-fermion compound URu 2 Si 2 undergoes a 2nd order phase transition at 17:5 K, yet the order parameter has remained hidden for over 20 years. This is an example of one of the most fundamental problems in solid state physics: the symmetries and associated order parameters are not obvious in many interesting systems. In fact, the order parameters of antiferromagnets (AF, staggered magnetization) and superconductors (SC, condensate wave function phase) were similarly hidden for many years. New discoveries of such nontrivial hidden-order systems (e.g., 2D XY magnets exhibit order of a purely topological character) thus continually expand our understanding of symmetry in solids.Most conceivable experimental probes have been utilized in an attempt to uncover the HO phase. Yet still, this diverse body of experimental data does not seem to convincingly converge to any existing model [2 -4]. For example, some characteristics of AF ordering occur: a large peak appears in the specific heat. However, the tiny observed staggered moment is inconsistent with the entropy lost at the transition [4], instead more likely due to a small AF impurity-phase [5]. Moreover, due to strong hybridization between the conduction electrons and nearly localized U-5f 2 moments, neither a purely local nor itinerantelectron model can be applied. Indeed, there is strong evidence for a Fermi-liquid comprised of ÿ 5 nonKramers doublet degrees of freedom [6,7].We present another route towards uncovering the HO in URu 2 Si 2 via thermal conductivity ( ) measurements. T undergoes a very large increase at the HO transition. Although this feature has been observed before [8,9], a model for T has not been obtained in a way that elucidates the HO. First, we explicitly show that T is dominated by phonons. We then apply a mean-field or BCS framework to describe ph whereby electron-phonon (e-ph) scattering decreases as a gap ( ) in the electronic density of states (DOS) opens at the HO transition. An unusually large 2 0 =k B T C ratio of 8 is needed in order to best describe the data, in agreement with point contact spectroscopy (PCS) estimates of , that...

show abstract

Section: Fig 2 (Color Online) (A)supporting

confidence: 79%

“…T undergoes a very large increase at the HO transition. Although this feature has been observed before [8,9], a model for T has not been obtained in a way that elucidates the HO. First, we explicitly show that T is dominated by phonons.…”

mentioning

confidence: 88%

Phonon Thermal Transport ofURu2Si2: Broken Translational Symmetry and Strong-Coupling of the “Hidden Order” to the Lattice

Sharma

Harrison²,

Jaime³

et al. 2006

Phys. Rev. Lett.

View full text Add to dashboard Cite

show abstract

“…The value of H c2 estimated experimentally by extrapolation to T = 0 for UBe 13 is about 80-130 kOe, which is much larger than the Pauli limit * E-mail address: yusei@phys.sci.hokudai.ac.jp H P (T =0) of 18.4 T c kOe (∼ 16.6 kOe for T c = 0.9 K). The paramagnetic effects might be thus considered to be absent in UBe 13 . However, this expression of H P is reliable only when a spin-orbit scattering by magnetic impurities can be neglected.…”

mentioning

confidence: 96%

“…The heavy-fermion compound UBe 13 has attracted much attention since the discovery of unconventional superconductivity 27 years ago. 1) UBe 13 has a cubic structure with the space group O h 6 (Fm−3c), and exhibits a superconducting (SC) transition at around 0.85 K with a large specific-heat jump ∆C.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Maki Parameter and Upper Critical Field of the Heavy-Fermion Superconductor UBe₁₃

et al. 2011

View full text Add to dashboard Cite

We have performed low-temperature specific-heat measurements in magnetic fields for a single crystal UBe 13 . It has been observed that our sample exhibits a superconducting transition at an intermediate temperature (T c ∼ 0.81 K) between previously reported values for two variant samples called H type and L type. The specific heat C(T ) of our sample shows a T 3 behavior below ∼ 0.7 T c , which is similar to the behavior of the H-type sample, suggesting the existence of point nodes in the superconducting gap function. We have obtained the upper-critical-field curves H c2 for the [001], [110], and [111] crystal axes, which show no anisotropy at least down to the lowest measured temperature of 0.5 K. We have also derived the Maki parameter κ 2 , and it has been revealed that the κ 2 steeply decreases isotropically upon cooling just below T c . Paramagnetic effects and the symmetry of Cooper pairing of UBe 13 are discussed. KEYWORDS: Unconventional Superconductor, Heavy Fermion, Paramagnetic EffectThe heavy-fermion compound UBe 13 has attracted much attention since the discovery of unconventional superconductivity 27 years ago. 1) UBe 13 has a cubic structure with the space group O h 6 (Fm−3c), and exhibits a superconducting (SC) transition at around 0.85 K with a large specific-heat jump ∆C. Despite prolonged scientific efforts to unravel the superconductivity of this material, many open questions remain, in particular concerning the symmetry of Cooper pairing and the unusual SC phase diagram. 2, 3)As for the SC gap structure, which is related to the parity of Cooper pairing, the temperature dependence of low-T specific heat C(T ) 4) and magnetic field penetration depth λ(T ) 5) suggest the presence of point nodes, whereas nuclear magnetic resonance (NMR) spin-relaxation rate 1/T 1 6) and ultrasonic attenuation α(T ) 7) suggest a line node. A p-wave AndersonBrinkman-Morel (ABM) state, which is identified as the A phase in superfluid 3 He,8) has been proposed for the SC of UBe 13 from the T 3 -like behavior observed in the low-T specific heat.4) An early NMR study also suggests the occurrence of the ABM state, because the Knight shift does not decrease below T c . 9) However, recent muon spin-rotation (µSR) measurements performed in field, H || [001], have revealed that the muon Knight shift shows a clear decrease below T c . 10)Furthermore, a recent NMR study by Tou et al. has suggested that the Knight shift decreases below T * ( ∼ 0.7 K < T c ) for [001], whereas increases below T * for [111]. 11) Therefore, no consensus has been achieved regarding the behavior of Knight shift below T c as well as the SC-gap structure. Namely, it is still debated whether the Cooper-pairing state of UBe 13 is triplet or singlet.In order to obtain further information about the parity of Cooper pairing, it is important to investigate the presence (or absence) of paramagnetic effects. The value of H c2 estimated experimentally by extrapolation to T = 0 for UBe 13 is about 80-130 kOe, which is much larger than the Pauli limit * E-mai...

show abstract

3.4.2.13 References for 3.4.2

Troć¹,

Suski²

Actinide Elements and Their Compounds With Other Elements. Part 2

View full text Add to dashboard Cite

Anisotropy of the upper critical field near Tc and the properties of URu2Si2 and UBe13 in the normal state

Cited by 32 publications

References 37 publications

Phonon Thermal Transport ofURu2Si2: Broken Translational Symmetry and Strong-Coupling of the “Hidden Order” to the Lattice

Phonon Thermal Transport ofURu2Si2: Broken Translational Symmetry and Strong-Coupling of the “Hidden Order” to the Lattice

Maki Parameter and Upper Critical Field of the Heavy-Fermion Superconductor UBe₁₃

3.4.2.13 References for 3.4.2

Contact Info

Product

Resources

About

Anisotropy of the upper critical field near Tc and the properties of URu2Si2 and UBe13 in the normal state

Cited by 32 publications

References 37 publications

Phonon Thermal Transport ofURu2Si2: Broken Translational Symmetry and Strong-Coupling of the “Hidden Order” to the Lattice

Phonon Thermal Transport ofURu2Si2: Broken Translational Symmetry and Strong-Coupling of the “Hidden Order” to the Lattice

Maki Parameter and Upper Critical Field of the Heavy-Fermion Superconductor UBe13

3.4.2.13 References for 3.4.2

Contact Info

Product

Resources

About

Maki Parameter and Upper Critical Field of the Heavy-Fermion Superconductor UBe₁₃