— Highlighted Publication —
●»Congratulations to Li Yong for publishing the article entitled with “Crystal growth and magnetic properties of LaMn0.91Sb2 and NdMn0.88Sb2”.
Abstract:： Square-net of Sb (Bi) layer lattice has attracted great attention because of its nontrivial topological band structure. In this work, we have successfully grown single crystals of LaMn0.91Sb2 and NdMn0.88Sb2 which have the square-net Sb lattice and study their complicated magnetism properties in detail. In LaMn0.91Sb2, the Mn atoms show signs of successive magnetic transitions. For NdMn0.88Sb2, magnetic Nd and Mn sublattices order antiferromagnetically on cooling. Magnetic phase diagrams are got by combining magnetism and heat capacity measurements.
●»Congratulations to Liu Hongxiong for publishing the article entitled with "Time-reversal symmetry-breaking charge order in a Kagome superconductor" in Nature as a co-author.
Abstract:：We observe a noticeable enhancement of the internal field width sensed by the muon ensemble, which takes place just below the charge ordering temperature and persists into the superconducting state. Notably, the muon spin relaxation rate below the charge ordering temperature is substantially enhanced by applying an external magnetic field. We further show the multigap nature of superconductivity in KV3Sb5 and that the Tc/λ-2ab is comparable to those of unconventional high-temperature superconductors. Our results point to time-reversal symmetry-breaking charge order intertwining with unconventional superconductivity in the correlated kagome lattice.
●» Ke Jia published his new work on Eu3InAs3 in Physical Review Research
Abstract:：We noticed the recent research by Kalpna Rajput about paramagnetic material Eu3InAs3. Therefore, we synthesized single crystals of Eu3InAs3 and studied their magnetic properties. We observed two antiferromagnetic transitions at 10 K and 13 K through both magnetic and specific heat measurements. Meanwhile, we found the emergence of 1/3 magnetization plateau and an anomaly at 2/3 of the saturated magnetization in Eu3InAs3, which may indicate the existence of magnetic frustration.
●» Cheng Tian published her new work on Ba5(OsO5)3Cl in Physical Review Materials
Abstract:：We found a new 5d ferromagnetic insulator Ba5(OsO5)3Cl and synthesized the poly- and single-crystalline samples. Ba5(OsO5)3Cl shows a ferromagnetic order below 5 K and a possible ferroelectric order below 150 K. The saturated magnetization for Ba5(OsO5)3Cl is close to the spin only value of 1 μB/Os7+. Theoretical calculations indicate that due to the large crystal field and spin splitting the SOC has little effect on the electronic band structure of Ba5(OsO5)3Cl.
●» Pengbo Song published his new work on SrIr2O6−δ in Physical Review B
Abstract: Strong spin-orbital-coupling magnetic systems with the honeycomb structure can provide bond-directional interactions which may result in Kitaev quantum spin liquids and exotic anyonic excitations. However, one of the key ingredients in real materials—disorders—has been much less studied in Kitaev systems. Here we synthesized a trigonal SrIr2O6−δ with δ ≈ 0.25, which consists of two-dimensional honeycomb Ir planes with edge-sharing IrO6 octahedra. First-principles computation and experimental measurements suggest that the electronic system is gapped, and there should be no magnetic moment as the Ir5+ ion has no unpaired electrons. However, significant magnetism has been observed in the material, and it can be attributed to disorders that are most likely from oxygen vacancies. No magnetic order is found down to 0.05 K, and the low-temperature magnetic properties exhibit power-law behaviors in magnetic susceptibility and zero-field specific heat, and a single-parameter scaling of the specific heat under magnetic fields. These results provide strong evidence for the existence of the random singlet phase in SrIr2O6−δ, which offers a different member to the family of spin-orbital entangled iridates and Kitaev materials.
●» Dayu Yan published his new work on MnSb2Te4 in Physical Review B
Abstract: MnSb2Te4 has been proposed to have magnetic topological states as a potential Weyl semimetal. We synthesized single crystals of MnSb2Te4 and systematically investigated their structural and physical properties. MnSb2Te4 has an isostructural septuple-layered structure that is similar to the magnetic topological insulator MnSb2Te4 but possesses transpositional Mn and Sb atoms between the sublayers. Magnetic and specific heat measurements revealed a ferrimagnetic phase transition with a Curie temperature TC of ∼31 K in MnSb2Te4, which originates from the interaction of the interexchanged Mn2+ ions. As the temperature decreases below TC, negative longitudinal magnetoresistance and anomalous Hall effect are observed, implying a non-negligible connection between the magnetism and expected transport carriers that may be driven by topological bands. Our results indicate that ferrimagnetic MnSb2Te4 provides insights for further studies on magnetic topological materials.
●» Dayu Yan published his research on TaC suoerconductor in Superconductor Science and Technology
Abstract: We report the synthesis and physical properties of the single crystals of TaC, which are proposed to hold topological band structure as a topological superconductor (TSC) candidate. Magnetization, resistivity and specific heat measurements are performed and indicate that TaC is bulk superconductor with critical temperature of 10.3 K. TaC is a strongly coupled type-II superconductor and the superconducting state can be well described by s-wave Bardeen–Cooper–Schrieffer theory with a single gap. The upper critical field (HC2) of TaC shows linear temperature dependence, which is quite different from most conventional superconductors and isostructural NbC, which is proposed to manifest topological nodal-loops or type-II Dirac points as well as superconductivity. Our results suggest that TaC would be a new candidate for further research of TSCs.
●» Cuixiang Wang published his new work about NdFe2Ga8 on Physical Review B
Abstract: We studied the magnetism in NdFe2Ga8 by magnetic susceptibility, specific heat, and resistivity measurements,which show Nd3+ ions forming one-dimensional chains along the c axis. At zero field, two magnetic transitions are found at about 15 and 11 K. For field vertical to the c axis, no significant effects on the magnetic orders are found. On the other hand, the two transitions are merged together at about 4 T for field parallel to the c axis and completely suppressed at about 7 T. The suppression of the magnetic order results in quantum critical behaviors of the conventional three-dimensional spin-density-wave type,such asρ 〜 T 1.5andC / T 〜 T -0.5。However, the temperature dependence of the resistivity is replaced by a T 0.5 behavior at very low temperatures for field larger than 3 T, which is attributed to the field-induced ferromagnetic moment. Our results suggest that there may be couplings between the antiferromagnetic quantum critical fluctuations and the field-induced ferromagnetic fluctuations.
●» Dayu Yan published his new work about NbC on Physical Review B
Abstract: We report the synthesis of single-crystal NbC, a transition metal carbide with various unusual properties. Transport, magnetic susceptibility, and specific heat measurements demonstrate that NbC is a conventional superconductor with a superconducting transition temperature (TC) of 11.5 K. Our theoretical calculations show that NbC is a type-II Dirac semimetal with strong Fermi-surface nesting, which is supported by our angle-resolved photoemission spectroscopy (ARPES) measurement results. We also observed the superconducting gaps of NbC using ARPES and found some unconventional behaviors. These intriguing superconducting and topological properties, combined with the high corrosion resistance, make NbC an ideal platform for both fundamental research and device applications.
●» Meng Yang published his new work about HoSbTe on Physical Review Materials
Abstract: We report the experimental and theoretical studies of a magnetic topological nodal line semimetal candidate HoSbTe. Single crystals of HoSbTe are grown from Sb flux, crystallizing in a tetragonal layered structure (space group: P4/nmm no. 129), in which the Ho-Te bilayer is separated by the square-net Sb layer. The magnetization and specific heat present distinct anomalies at ∼4 K related to an antiferromagnetic (AFM) phase transition. Meanwhile, with applying magnetic field perpendicular and parallel to the crystallographic c axis, an obvious magnetic anisotropy is observed. Electrical resistivity undergoes a bad-metal-like state below 200 K and reveals a plateau at about 8 K followed by a drop due to the AFM transition. In addition, with the first-principle calculations of band structure, we find that HoSbTe is a topological nodal line semimetal or a weak topological insulator with or without taking the spin-orbit coupling into account, providing a platform to investigate the interplay between magnetic and topological fermionic properties.
●» Meng Yang published his new work about PrPd0.82Bi2 on Chinese Review B
Abstract: We report the physical properties, crystalline and magnetic structures of singe crystals of a new layered antiferromagnetic(AFM) material PrPd0.82Bi2. The measurements of magnetic properties and heat capacity indicate an AFM phase transition at TN 〜 7 K. A large Sommerfeld coefficient of 329.23 mJ·mol-1·K-2，is estimated based on the heat capacity data, implying a possible heavy-fermion behavior. The magnetic structure of this compound is investigated by a combined study of neutron powder and single-crystal diffraction.It is found that an A-type AFM structure with magnetic propagation wavevector k = (0 0 0) is formed below TN.Pr3+magnetic moment is aligned along the crystallographic c axis with an ordered moment of 1.694(3) μB at 4 K，which is smaller than the effective moment of the free Pr3+ ion of (3.58 μB). PrPd0.82Bi2 can be grown as large as 1 mm×1 cm in area with a layered shape, and is very easy to be cleaved, providing a unique opportunity to study the interplay between magnetism, possible heavy fermions, and superconductivity.
●» Le Wang published his new work about CePd2Al8 on Physical Review B
Abstract: We report the synthesis and detailed investigation of the single crystal CePd2Al8. Resistivity measurements reveal typical metallic behavior at high temperatures and a plateau at about 15 K followed by a rapid drop due to successive antiferromagnetic（AFM）and ferromagnetic （FM）transitions. We find an extremely large magnetic anisotropy with χa/χb › 2000 at 2. With increasing magnetic field, the AFM transition temperature is gradually suppressed and only the ferromagnetic phase remains above 500 Oe for Ha, with an ordered moment of 1.43 μB, while for Hb，the FM transition turns into an AFM-like transition. With pressure, the two phases merge at 12.5 GPa into a possibly ferromagnetic phase, pointing to a possible critical point at higher pressures. We construct the temperature-magnetic field and temperature-pressure phase diagrams for the single crystal CePd2Al8.
●» Meng Yang published his new work about Zr1-xNbxCo2Sn on Journal of Physics: Condensed Matter
Abstract: ZrCo2Snis a potential candidate as a Weyl semimetal with a ferromagnetic ground state, and Nb-doping is expected to shift the Weyl points to the vicinity of Fermi level. We successfully synthesized a series ofZr1-xNbxCo2Sn single crystals with various concentrations of Nb（x = 0，0.1，0.2，0.275，0.4，0.5）. All samples have a spinel structure and the lattice constant decrease as the Nb doping level increases. The magnetization and transport measurements suggest that the ferromagnetic ordering temperature can be strongly modified by the Nb doping. When x increases, the Curie temperature decreases significantly, accompanied by a change from metal-like to semiconductor-like behavior. There is a crossover for positive to negative MR at a temperature between 30 K to 50 K. In constant, the magnitude of the anomalous Hall resistance increases monotonously with decreasing temperature.
●» Zili Feng published his new work about new quantum spin liquid meterial Cu3Zn(OH)6FCl on Chinese Physics Letter.
Abstract: The search for quantum spin liquid (QSL) materials has attracted significant attention in the field of condensed matter physics in recent years, however so far only a handful of them are considered as candidates hosting QSL ground state. Owning to their geometrically frustrated structures, Kagome materials are ideal systems to realize QSL. We synthesize the kagome structured material claringbullite (Cu4(OH)6FCl) and then replace inter-layer Cu with Zn to form Cu3Zn(OH)6FCl. Comprehensive measurements reveal that doping Zn2+ ions transforms magnetically ordered Cu4(OH)6FCl into a non-magnetic QSL candidate Cu3Zn(OH)6FCl. Therefore, the successful syntheses of Cu4(OH)6FCl and Cu3Zn(OH)6FCl provide not only a new platform for the study of QSL but also a novel pathway of investigating the transition between QSL and magnetically ordered systems.
●» Zili Feng published his new work about Cu4-xZnx(OH)6FBr on Physical Review B
Abstract: Barlowite Cu4(OH)6FBr shows three-dimensional (3D) long-range antiferromagnetism, which is fully suppressed in Cu3Zn(OH)6FBr with a kagome quantum spin liquid ground state. Here we report systematic studies on the evolution of magnetism in the Cu4-xZnx(OH)6FBr system as a function of x to bridge the two limits of Cu4(OH)6FBr(x=0) and Cu3Zn(OH)6FBr(x=1). Neutron-diffraction measurements reveal a hexagonal-to-orthorhombic structural change with decreasing temperature in the x=0 sample. While confirming the 3D antiferromagnetic nature of low-temperature magnetism, the magnetic moments on some Cu2+ sites on the kagome planes are found to be vanishingly small, suggesting strong frustration already exists in barlowite. Substitution of interlayer Cu2+ with Zn2+ with gradually increasing x completely suppresses the bulk magnetic order at around x=0.4 but leaves a local secondary magnetic order up to x∼0.8 with a slight decrease in its transition temperature. The high-temperature magnetic susceptibility and specific-heat measurements further suggest that the intrinsic magnetic properties of kagome spin liquid planes may already appear from x>0.3 samples. Our results reveal that the Cu4-xZnx(OH)6FBr may be the long-thought experimental playground for the systematic investigations of the quantum phase transition from a long-range antiferromagnet to a topologically ordered quantum spin liquid.
●» Le Wang published his new work about CeCoInGa3 on Physical Review B
Abstract: We report a detailed and comparative study of the single-crystal CeCoInGa3 in both experiment and theory. Resistivity measurements reveal the typical behavior of a Kondo lattice with the onset temperature of coherence, T* ≈ 50K. The magnetic specific heat can be well fitted using a spin-fluctuation model at low temperatures, yielding a large Sommerfeld coefficient, γ ≈ 172 mJ/mol K2 at 6K, suggesting that this is a heavy-fermion compound with a pronounced coherence effect. The magnetic susceptibility exhibits a broad field-independent peak at Tχ and shows an obvious anisotropy within the bc plane, reflecting the anisotropy of the coherence effect at high temperatures. These are compared with strongly correlated calculations combining first-principles band structure calculations and dynamical mean-field theory. Our results confirm the onset of coherence at about 50K and reveal a similar anisotropy in the hybridization gap, pointing to a close connection between the hybridization strength of the low-temperature Fermi-liquid state and the high-temperature coherence effect.
●» Changjiang Yi published his research work on the growth of single crystal of topological materials in Acta Physica Sinca
Abstract: Topological semimetals have attracted much attention and become a hot subject in condensed matter physics,and single crystal growth is the basis of the physical investigation on these materials. At present, the research oftopological materials has formed a cooperation circle: presenting materials by theoretical calculation; single crystalgrowth; verification by experiments on single crystals. Single crystal growth has become a bridge between theory andexperiment. Here in this paper, we introduce the single crystal growth of the topological semimetals presented inrecent years, including topological Dirac semimetals, Weyl semimetals, Node-Line semimetals and other new classes oftopological materials. The detailed growth methods are summarized in this paper for each material.
●» Changjiang Yi published his new work about TiB2 on Physical Review B
Abstract: Topological nodal-line semimetals (TNLSMs) are characterized by symmetry-protected band crossings extending along one-dimensional lines in momentum space. The nodal lines exhibit a variety of possible configurations, such as nodal ring, nodal link, nodal chain, and nodal knot. Here, using angle-resolved photoemission spectroscopy, we observe nodal rings on the orthogonal Kz = 0 and Kx = 0 planes of the Brillouin zone in TiB2. The nodal rings connect with each other on the intersecting line Γ-K of the orthogonal planes forming a remarkable nodal-chain structure. Furthermore, we observe surface states (SSs) on the (001) cleaved surface, which are consistent with the calculated SSs considering the contribution from both Ti and B terminations. The calculated SSs have novel Dirac-cone-like band structures, which are distinct from the usual drumhead SSs with a single flatband proposed in other TNLSMs.
●» Changjiang Yi published his new work about EuMnSb2 on Physical Review B
Abstract: We report an experimental study of the magnetic order and electronic structure and transport of the layered pnictide EuMnSb2, performed using neutron diffraction, angle-resolved photoemission spectroscopy (ARPES), and magnetotransport measurements. We find that the Eu and Mn sublattices display antiferromagnetic (AFM) order below TNEu = 21(1)K and TNMn = 350(2)K, respectively. The former can be described by an A-type AFM structure with the Eu spins aligned along the c axis (an in-plane direction), whereas the latter has a C-type AFM structure with Mn moments along the a -axis (perpendicular to the layers). The ARPES spectra reveal Dirac-like linearly dispersing bands near the Fermi energy. Furthermore, our magnetotransport measurements show strongly anisotropic magnetoresistance and indicate that the Eu sublattice is intimately coupled to conduction electron states near the Dirac point.
●» Le Wang published his new work about CeCo2Gab on NPJ Quantum Materials
Abstract: Dimensionality plays an essential role in determining the anomalous non-Fermi liquid properties in heavy fermion systems. So far most heavy fermion compounds are quasi-two-dimensional or three-dimensional. Here we report the synthesis and systematic investigations of the single crystals of the quasi-one-dimensional Kondo lattice CeCo2Ga8. Resistivity measurements at ambient pressure reveal the onset of coherence at T* ≈ 20 K and non-Fermi liquid behavior with linear temperature dependence over a decade in temperature from 2 to 0.1 K. The specific heat increases logarithmically with lowering temperature between 10 and 2 K and reaches 800 mJ / mol K2，suggesting that CeCo2Ga8is a heavy fermion compound in the close vicinity of a quantum critical point. Resistivity measurements under pressure further confirm the non-Fermi liquid behavior in a large temperature–pressure range. The magnetic susceptibility is found to follow the typical behavior for a one-dimensional spin chain from 300 K down to T*, and first-principles calculations predict flat Fermi surfaces for the itinerant f-electron bands. These suggest that CeCo2Ga8is a rare example of the quasi-one-dimensional Kondo lattice, but its non-Fermi liquid behaviors resemble those of the quasi-two-dimensional YbRh2Si2 family. The study of the quasi-one-dimensional CeCo2Ga8 family may therefore help us to understand the role of dimensionality on heavy fermion physics and quantum criticality.
●» Zili Feng published his new work about Cu3Zn(OH)6FBr on Chinese Physics Letter
Abstract: We report a new kagome quantum spin liquid candidate Cu3Zn(OH)6FBr，which does not experience any phase transition down to 50 mK, more than three orders lower than the antiferromagnetic Curie-Weiss temperature（〜200 K）. A clear gap opening at low temperature is observed in the uniform spin susceptibility obtained from 19F nuclear magnetic resonance measurements. We observe the characteristic magnetic field dependence of the gap as expected for fractionalized spin1/2spinon excitations. Our experimental results provide firm evidence for spin fractionalization in a topologically ordered spin system, resembling charge fractionalization in the fractional quantum Hall state.
