Needle-like single crystals of CeAu_(2)In_(4)have been grown from In flux and characterized as a new candidate of quasi-one-dimensional Kondo lattice compound by crystallographic,magnetic,transport,and specific-heat m...Needle-like single crystals of CeAu_(2)In_(4)have been grown from In flux and characterized as a new candidate of quasi-one-dimensional Kondo lattice compound by crystallographic,magnetic,transport,and specific-heat measurements down to very low temperatures.We observe an antiferromagnetic transition at T_(N)≈0.9 K,a highly non-mean-field profile of the corresponding peak in specific heat,and a large Sommerfeld coefficientγ=369 mJ·mol^(-1)·K^(-2).The Kondo temperature T_(K)is estimated to be 1.1 K,being low and comparable to TN.While Fermi liquid behavior is observed deep into the magnetically ordered phase,the Kadowaki-Woods ratio is much reduced relative to the expected value for Ce compounds with Kramers doublet ground state.Markedly,this feature shares striking similarities to that of the prototypical quasi-one-dimensional compounds YbNi_(4)P_(2) and CeRh_(6)Ge_(4) with tunable ferromagnetic quantum critical point.Given the shortest Ce-Ce distance along the needle direction,CeAu_(2)In_(4)appears to be an interesting model system for exploring antiferromagnetic quantum critical behaviors in a quasi-one-dimensional Kondo lattice with enhanced quantum fluctuations.展开更多
CePdAl has been recently recognized as a frustrated antiferromagnetic heavy-fermion compound with a pressureor field-tuned,extended quantum critical phase at zero temperature.Identifying characteristic signatures of t...CePdAl has been recently recognized as a frustrated antiferromagnetic heavy-fermion compound with a pressureor field-tuned,extended quantum critical phase at zero temperature.Identifying characteristic signatures of the emerging quantum critical phase,which are expected to be distinct from those near a quantum critical point,remains challenging.In this work,by performing ultrasonic and thermoelectric measurements down to very low temperatures in a^(3)He–^(4)He dilution refrigerator in the presence of magnetic field,we are able to obtain some crucial thermodynamic and thermal transport features of the quantum critical phase,including a frustration-related elastic softening detected by ultrasound and a Fermi-surface change probed by thermoelectric effect.展开更多
By studying the thermal conductivity,specific heat,elastic modulus,and thermal expansion as a function of temperature for Cd_(3)As_(2),we have unveiled a couple of important thermodynamic features of the low-energy ph...By studying the thermal conductivity,specific heat,elastic modulus,and thermal expansion as a function of temperature for Cd_(3)As_(2),we have unveiled a couple of important thermodynamic features of the low-energy phonons strongly interacting with Dirac electrons.The existence of soft optical phonons,as inferred from the extremely low thermal conductivity,is unambiguously confirmed by low-temperature specific heat revealing significant deviation from Debye's description.The estimated Debye temperature is small in the range of 100-200 K and varies significantly depending upon the measurement used in its experimental determination.The thermodynamic Gr¨uneisen ratioγreveals a remarkable reduction below about 100 K,an energy scale that is highly relevant to the Dirac states,towards negative values below about 10 K that are indicative of lattice instability.展开更多
Kondo semimetal CeRu4Sn6 is attracting renewed attention due to the theoretically predicted nontrivial topology in its electronic band structure. We report hydrostatic and chemical pressure effects on the transport pr...Kondo semimetal CeRu4Sn6 is attracting renewed attention due to the theoretically predicted nontrivial topology in its electronic band structure. We report hydrostatic and chemical pressure effects on the transport properties of single- and poly-crystalline samples. The electrical resistivity p (T) is gradually enhanced by applying pressure over a wide temperature range from room temperature down to 25 mK. Two thermal activation gaps estimated from high- and low-temperature windows are found to increase with pressure. A flat p(T) observed at the lowest temperatures below 300 mK appears to be robust against both pressure and field. This feature as well as the increase of the energy gaps calls for more intensive investigations with respect to electron correlations and band topology.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774404 and 52088101)the National Key R&D Program of China(Grant No.2017YF A0303100)the Chinese Academy of Sciences through the Strategic Priority Research Program(Grant No.XDB33000000).
文摘Needle-like single crystals of CeAu_(2)In_(4)have been grown from In flux and characterized as a new candidate of quasi-one-dimensional Kondo lattice compound by crystallographic,magnetic,transport,and specific-heat measurements down to very low temperatures.We observe an antiferromagnetic transition at T_(N)≈0.9 K,a highly non-mean-field profile of the corresponding peak in specific heat,and a large Sommerfeld coefficientγ=369 mJ·mol^(-1)·K^(-2).The Kondo temperature T_(K)is estimated to be 1.1 K,being low and comparable to TN.While Fermi liquid behavior is observed deep into the magnetically ordered phase,the Kadowaki-Woods ratio is much reduced relative to the expected value for Ce compounds with Kramers doublet ground state.Markedly,this feature shares striking similarities to that of the prototypical quasi-one-dimensional compounds YbNi_(4)P_(2) and CeRh_(6)Ge_(4) with tunable ferromagnetic quantum critical point.Given the shortest Ce-Ce distance along the needle direction,CeAu_(2)In_(4)appears to be an interesting model system for exploring antiferromagnetic quantum critical behaviors in a quasi-one-dimensional Kondo lattice with enhanced quantum fluctuations.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0303100)the National Natural Science Foundation of China(Grant Nos.12141002,52088101,and 11974389)+2 种基金the Fund of the Chinese Academy of Sciences through the Scientific Instrument Developing Project(Grant No.ZDKYYQ20210003)the Strategic Priority Research Program(Grant No.XDB33000000)by China Postdoctoral Science Foundation(Grant No.2020TQ0349)。
文摘CePdAl has been recently recognized as a frustrated antiferromagnetic heavy-fermion compound with a pressureor field-tuned,extended quantum critical phase at zero temperature.Identifying characteristic signatures of the emerging quantum critical phase,which are expected to be distinct from those near a quantum critical point,remains challenging.In this work,by performing ultrasonic and thermoelectric measurements down to very low temperatures in a^(3)He–^(4)He dilution refrigerator in the presence of magnetic field,we are able to obtain some crucial thermodynamic and thermal transport features of the quantum critical phase,including a frustration-related elastic softening detected by ultrasound and a Fermi-surface change probed by thermoelectric effect.
基金supported by the National Natural Science Foundation of China(Grant Nos.11974389,12141002 and 52088101)the National Key R&D Program of China(Grant No.2017YFA0303100)+1 种基金the Chinese Academy of Sciences through the Scientific Instrument Developing Project(Grant No.ZDKYYQ20210003)the Strategic Priority Research Program(Grant No.XDB33000000)。
文摘By studying the thermal conductivity,specific heat,elastic modulus,and thermal expansion as a function of temperature for Cd_(3)As_(2),we have unveiled a couple of important thermodynamic features of the low-energy phonons strongly interacting with Dirac electrons.The existence of soft optical phonons,as inferred from the extremely low thermal conductivity,is unambiguously confirmed by low-temperature specific heat revealing significant deviation from Debye's description.The estimated Debye temperature is small in the range of 100-200 K and varies significantly depending upon the measurement used in its experimental determination.The thermodynamic Gr¨uneisen ratioγreveals a remarkable reduction below about 100 K,an energy scale that is highly relevant to the Dirac states,towards negative values below about 10 K that are indicative of lattice instability.
基金Project supported by the Ministry of Science and Technology of China(Grant Nos.2015CB921303 and 2017YFA0303103)the National Natural Science Foundation of China(Grant Nos.11474332 and 11774404)the Chinese Academy of Sciences through the Strategic Priority Research Program(Grant No.XDB07020200)
文摘Kondo semimetal CeRu4Sn6 is attracting renewed attention due to the theoretically predicted nontrivial topology in its electronic band structure. We report hydrostatic and chemical pressure effects on the transport properties of single- and poly-crystalline samples. The electrical resistivity p (T) is gradually enhanced by applying pressure over a wide temperature range from room temperature down to 25 mK. Two thermal activation gaps estimated from high- and low-temperature windows are found to increase with pressure. A flat p(T) observed at the lowest temperatures below 300 mK appears to be robust against both pressure and field. This feature as well as the increase of the energy gaps calls for more intensive investigations with respect to electron correlations and band topology.