Elastic properties of the heavy fermion superconductor URu2Si2

Wolf, B.; Sixl, W.; Graf, R.; Finsterbusch, D.; Bruls, G.; Lüthi, B.; Knetsch, E.A.; Menovsky, A.A.; Mydosh, J. A.

doi:10.1007/bf00754672

Cited by 38 publications

(33 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…24,25) Moreover, the magnetic-field dependence of À À3 for H k ½001 does not show any anomaly at the suppression of the HO, while the calculated c-axis magnetic susceptibility shows a jump at H 1 . These discrepancies simply show the limitations of the present localized-electron model to describe the elastic responses.…”

mentioning

confidence: 81%

“…Early studies employing ultrasonic measurements on URu 2 Si 2 uncovered a characteristic decrease (softening) of the elastic constant C 11 and ðC 11 À C 12 Þ=2 with decreasing temperature. 24,25) The softening of C 11 had been explained by Grüneisen coupling due to many-body effects, which appears in the bulk modulus of typical heavy-fermion compounds. This phenomena is the so-called Kondo-volume collapse.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Γ₃-Type Lattice Instability and the Hidden Order of URu₂Si₂

et al. 2013

View full text Add to dashboard Cite

We have performed ultrasonic measurements on single-crystalline URu 2 Si 2 with pulsed magnetic fields, in order to check for possible lattice instabilities due to the hybridized state and the hidden-order state of this compound. The elastic constant ðC 11 À C 12 Þ=2, which is associated with a response to the À 3 -type symmetry-breaking (orthorhombic) strain field, shows a three-step increase at H ! 35 T for H k c at low temperatures, where successive meta-magnetic transitions are observed in the magnetization. We discovered a new fact that the absolute change of the softening of ðC 11 À C 12 Þ=2 in the temperature dependence is quantitatively recovered at the suppression of hybridized-electronic state and the hidden order in high-magnetic field for H k c associated with the successive transitions. The present results suggest that the À 3 -type lattice instability, is related to both the emergence of the hybridized electronic state and the hidden-order parameter of URu 2 Si 2 . On the other hand, magnetic fields H k ½100 and [110] enhance the softening of ðC 11 À C 12 Þ=2 in the hidden order phase, while no step-like anomaly is observed up to 68.7 T. We discuss the limitation of the localized-electron picture for describing these features of URu 2 Si 2 by examination of a crystalline electric field model in terms of mean-field theory.KEYWORDS: URu 2 Si 2 , hidden order, elastic constant, ultrasound, pulsed-magnetic field ''What is the primary order parameter and its ordering vector for the hidden order of URu 2 Si 2 ?'' is still an open and controversial question and a longstanding issue of condensed matter physics. 1) URu 2 Si 2 , which crystallizes in the ThCr 2 Si 2 -type tetragonal structure (space group No. 139, I4=mmm), shows an unknown second-order transition at T o ¼ 17:5 K, known as the hidden order (HO) phase, and also a transition into an unconventional superconducting state below T c $ 1:4 K. 1-3) Many theoretical models have been proposed from both localized and itinerant electron pictures in attempts to identify the order parameter of the HO phase. Since 29 Si-NMR and zero-magnetic-field SR measurements have detected little ( 1 G) or no significant internal-magnetic field in the HO phase, 4-6) non-dipolar-type order parameters, e.g., electric quadrupole (rank 2), hexadecapole (rank 4), À 3 -type magnetic octupole (rank 3), or dotriacontapole (rank 5) order parameters, are recently attracting attention. 7-13) Thus far, none of the characteristic signatures of the electric-quadrupole or magnetic-octupole order has been identified in resonant X-ray scattering (under magnetic fields) and neutron scattering under uniaxial stress. 14,15) On the other hand, a nematicity of the electron state in the HO is pointed out, since an in-plane rotational four-fold symmetry breaking is observed in the HO by the magnetic-torque measurement by use of cantilever technique. 16) The interpretation of these experimental results remains controversial.URu 2 Si 2 is also considered a heavy-fermion compound since several ph...

show abstract

mentioning

confidence: 81%

mentioning

confidence: 99%

Γ₃-Type Lattice Instability and the Hidden Order of URu₂Si₂

et al. 2013

View full text Add to dashboard Cite

show abstract

“…However, despite various attempts to find periodic lattice distortions, none have been found. Solid state probes that are sensitive to the local symmetry like NMR/NQR would be able to detect these, but none have been found (Saitoh et al, 2005).The elastic properties of URu 2 Si 2 have been measured with ultrasonic techniques (Kuwahara et al, 1997;Wolf et al, 1994). A softening is observed in the c 11 and transversal (c 11 − c 12 )/2 modes at temperatures below 7 ∼ 70 K, marking the onset of the coherence temperature (Kuwahara et al, 1997).…”

mentioning

confidence: 99%

“…The elastic anomalies observed at T o are in contrast quite small, indicating that no uniform distortion occurs at T o . The longitudinal c 11 shows a broad minimum at 30 K and increases slightly (∼ 0.1%) when temperature is lowered (Kuwahara et al, 1997;Wolf et al, 1994).Point-contact spectroscopy (PCS) measurements at temperatures around T o have been applied to detect the opening of a conductance gap in the HO state (Escudero et al, 1994;Hasselbach et al, 1992;Morales and Escudero, 2009;Rodrigo et al, 1997;Thieme et al, 1995). All PCS data generally evidence the opening of such gap, however, its onset is consistently found at about 19-25 K and not at T o .…”

mentioning

confidence: 99%

Colloquium: Hidden order, superconductivity, and magnetism: The unsolved case ofURu2Si2

2011

Self Cite

View full text Add to dashboard Cite

This Colloquium reviews the 25 year quest for understanding the continuous (2 nd ) order, meanfield-like phase transition occurring at 17.5 K in URu 2 Si 2 . Since ca. ten years the term hidden order (HO) has been coined and utilized to describe the unknown ordered state, whose origin cannot be disclosed by conventional solid-state probes, such as x-rays, neutrons, or muons. HO is able to support superconductivity at lower temperatures (Tc ≈ 1.5 K) and when magnetism is developed with increasing pressure both the HO and the superconductivity are destroyed. Other ways of probing the HO are via Rh-doping and very large magnetic fields. During the last few years a variety of advanced techniques have been tested to probe the HO state and their attempts will be summarized. A digest of recent theoretical developments is also included. It is the objective of this survey to shed additional light on the HO state and its associated phases in other materials. VII. Present State of HO 12Acknowledgments 16 References 17Figures 21 I. HISTORICAL BACKGROUNDUranium is a most intriguing element, not only in itself but also as a basis for forming a variety of compounds and alloys with unconventional or puzzling physics properties (for recent reviews, see Sechovský and Havela (1998), Santini et al. (1999), Stewart (2006)). Natural or depleted uranium, i.e. containing 99.5 percent 238 U has a * Electronic address: mydosh@physics.leidenuniv.nl † Electronic address: peter.oppeneer@physics.uu.se mild alpha radioactivity of 25 kBq/g, which allows Ubased samples to be fabricated and studied in university laboratories with a minimum of safety precautions. Following initial discoveries of unexpected superconductivity and heavy-fermion behavior in uranium-based compounds as UBe 13 (Ott et al., 1983) and UPt 3 (Stewart et al., 1984) it has become popular to synthesize uranium compounds and to cool these in search for exotic ground states. Over the past 50 or so years many conducting and insulating systems were synthesized, analyzed and structurally characterized (Sechovský and Havela, 1998;Stewart, 2001Stewart, , 2006. The usual classification of the metallic samples at low temperature is superconducting and/or magnetic or with some of the modern compounds designated as "exotic" (Pfleiderer, 2009).Why are uranium-based materials so interesting? The observed variety of unusual behaviors derive directly from the U open 5f shell. Several defining electronic structure quantities of the U f electrons are all on the same energy scale: the exchange interaction, 5f bandwidth, the spin-orbit interaction, and intra-atomic f − f Coulomb interaction. As a consequence, i) elemental uranium displays intermediate behavior between the transition metals and the rare-earths in their characteristic bandwidths, yet it generates the largest spin-orbit coupling. ii) U lies directly on the border between localized and itinerant (or overlapping) 5f wavefunctions. iii) The WignerSeitz radii R WS of comparative elements places U near the minimum between metallic and...

show abstract

“…As the atomic form factors for x-ray scattering are proportional to Z, this can only occur for optic modes with eigenvectors dominated by the silicon atoms. The dashed lines are the speeds of sound calculated from ultrasound measurements from Yanigisawa et al along Γ to Σ and Γ to X and from Wolf et al along Γ to Z [33,34]. We did not measure any temperature dependence to the dispersion between 300K and 8K.…”

Section: Energy (Mev)mentioning

confidence: 86%