Magnetism and magnetocaloric effect in TlCo Ni S (0 [Formula: see text] x [Formula: see text] 0.05).

We have investigated the magnetism and magnetocaloric effect of TlCo Ni S (0 [Formula: see text] x [Formula: see text] 0.05). TlCoS and TlCoNiS are ferromagnetically ordered below 153 K and 142 K with saturated moment 0.

Large magnetoresistance and large magnetothermopower effect in the Dirac material EuMnSb.

In this article, the structure, transport and magnetic properties were studied in details for EuMnSb crystals with the orthorhombic structure and Mn deficiencies. It was found that the temperature dependence of the resistivity exhibits a metallic behavior in the whole measuring temperature range, different from that in the crystals without Mn deficiencies. A large positive magnetoresistance (MR) (∼127% at 2 K and  ∼25% at 300 K, in 9 T field) was observed, which can be ascribed to the combination of semiclassical MR and quantum limit MR of Dirac electrons.

Critical properties of the quasi-two-dimensional metallic ferromagnet FeGeTe.

We have investigated the critical behavior of FeGeTe single crystals near the paramagnetic-ferromagnetic transition by bulk dc magnetization measurements. The critical exponents β, γ and δ, obtained from modified Arrott plot, Kouvel-Fisher method, and critical isothermal magnetization analysis, could fulfill the Widom scaling law. The self-consistency and reliability of these exponents are further verified by the magnetic state equations below and above the Curie temperature at high magnetic field.

From tricritical ferromagnetism to metamagnetism in quasi-two dimensional Tl(Co Ni )S (x = 0, 0.05).

We have investigated the critical behavior near the ferromagnetic transition of TlCoS single crystals and the magnetic properties of Tl(CoNi)S by means of magnetization measurements. The obtained critical exponents β, γ and δ of TlCoS could basically satisfy the scaling equations and are found very close to the prediction of the tricritical mean-field theory. 5[Formula: see text] Ni doping drives the system to an antiferromagnetic ground state which is unstable to magnetic field, yielding metamagnetic transition.

Pressure induced superconductivity in the antiferromagnetic Dirac material BaMnBi.

The so-called Dirac materials such as graphene and topological insulators are a new class of matter different from conventional metals and (doped) semiconductors. Superconductivity induced by doing or applying pressure in these systems may be unconventional, or host mysterious Majorana fermions. Here, we report a successfully observation of pressure-induced superconductivity in an antiferromagnetic Dirac material BaMnBi with T of ~4 K at 2.

Large low field magnetocaloric effect in first-order phase transition compound TlFeTe with low-level hysteresis.

Magnetic refrigeration based on the magnetocaloric effect (MCE) is an environment-friendly, high-efficiency technology. It has been believed that a large MCE can be realized in the materials with a first-order magnetic transition (FOMT). Here, we found that TlFeTe is a ferromagnetic metal with a first-order magnetic transition occurring at Curie temperature T = 220 K.

Superconductivity and disorder effect in TlNi2Se(2-x)S(x) compounds.

After our first discovery of multi-band superconductivity (SC) in the TlNi2Se2 crystal, we successfully grew a series of TlNi2Se(2-x)S(x) (0.0 ≤ x ≤ 2.0) single crystals.

Multiband superconductivity of heavy electrons in a TlNi2Se2 single crystal.

We have made the first observation of superconductivity in TlNi2Se2 at T(C)=3.7  K, and it appears to involve heavy electrons with an effective mass m*=(14-20)m(b), as inferred from the normal-state electronic specific heat and the upper critical field, H(C2)(T). We found that the zero-field electronic specific-heat data, C(es)(T) (0.

Phase diagram and annealing effect for Fe1+δTe1-xSx single crystals.

The excess Fe atoms which unavoidably exist in the Fe(Te, Se, S) crystal lattice result in a complicated antiferromagnetic ground state as well as the suppression of superconductivity. As a result, there are still discrepancies on their phase diagrams. In this paper, we report the synthesis of Fe1+δTe1-xSx (0 ≤ x ≤ 0.

Magnetic ordering in semiconducting Tl0.53K0.47Fe1.64Se2 single crystals studied by Mössbauer spectroscopy.

The results of a 57Fe Mössbauer spectroscopy study between 4.5 and 523.2 K and in external magnetic fields (up to 90 kOe) of semiconducting Tl0.

Re-emerging superconductivity at 48 kelvin in iron chalcogenides.

Pressure has an essential role in the production and control of superconductivity in iron-based superconductors. Substitution of a large cation by a smaller rare-earth ion to simulate the pressure effect has raised the superconducting transition temperature T(c) to a record high of 55 K in these materials. In the same way as T(c) exhibits a bell-shaped curve of dependence on chemical doping, pressure-tuned T(c) typically drops monotonically after passing the optimal pressure.

Common crystalline and magnetic structure of superconducting A2Fe4Se5 (A=K,Rb,Cs,Tl) single crystals measured using neutron diffraction.

Single-crystal neutron diffraction studies on superconductors A(2)Fe(4)Se(5), where A=Rb, Cs, (Tl, Rb), and (Tl, K) (T(c) ∼ 30 K), uncover the same Fe vacancy ordered crystal structure and the same block antiferromagnetic order as in K(2)Fe(4)Se(5). The Fe order-disorder transition occurs at T(S)=500-578 K, and the antiferromagnetic transition at T(N) = 471-559 K with an ordered magnetic moment ∼3.3μ(B)/Fe at 10 K.

Distinct fermi surface topology and nodeless superconducting gap in a (Tl0.58Rb0.42)Fe1.72Se2 superconductor.

High resolution angle-resolved photoemission measurements have been carried out to study the electronic structure and superconducting gap of the (Tl0.58Rb0.42)Fe1.

Band narrowing and Mott localization in iron oxychalcogenides La2O2Fe2O(Se,S)2.

Bad metal properties have motivated a description of the parent iron pnictides as correlated metals on the verge of Mott localization. What has been unclear is whether interactions can push these and related compounds to the Mott-insulating side of the phase diagram. Here we consider the iron oxychalcogenides La2O2Fe2O(Se,S)2, which contain an Fe square lattice with an expanded unit cell.

Spin gap and resonance at the nesting wave vector in superconducting FeSe_{0.4}Te_{0.6}.

Neutron scattering is used to probe magnetic excitations in FeSe_{0.4}Te_{0.6} (T_{c} = 14 K).

Tunable (deltapi, deltapi)-type antiferromagnetic order in alpha-Fe(Te,Se) superconductors.

The new alpha-Fe(Te,Se) superconductors share the common iron building block and ferminology with the LaFeAsO and BaFe(2)As(2) families of superconductors. In contrast with the predicted commensurate spin-density-wave order at the nesting wave vector (pi, 0), a completely different magnetic order with a composition tunable propagation vector (deltapi, deltapi) was determined for the parent compound Fe_{1+y}Te in this powder and single-crystal neutron diffraction study. The new antiferromagnetic order survives as a short-range one even in the highest T_{C} sample.