We report the discovery of superconductivity on high-quality single crystals of transition-metal pnictides WP grown by chemical vapor transport (CVT) method.Bulk superconductivity is observed at T c = 0.84 K under ambient pressure by electrical resistivity and AC magnetic susceptibility measurements. The effects of magnetic field on the superconducting transitions are studied, leading to a large anisotropy parameter around 2 with the in-plane and out-of-plane upper critical fields of 2,∥ =172 Oe and 2,⊥ =85 Oe, respectively. Our finding demonstrates that WP is the first superconductor in 5d transition-metal at ambient pressure in MnP-type, which will help to search for new superconductors in transition-metal pnictides.

Recently, the theoretically predicted lanthanum superhydride, LaH10 ± δ , with a clathrate-like structure was successfully synthesized and found to exhibit a record high superconducting transition temperature T c ≈ 250 K at ∼ 170 GPa, opening a new route for room-temperature superconductivity. However, since in situ experiments at megabar pressures are very challenging, few groups have reported the ∼ 250 K superconducting transition in LaH10 ± δ . Here, we establish a simpler sample-loading procedure that allows a relatively large sample size for synthesis and a standard four-probe configuration for resistance measurements. Following this procedure, we successfully synthesized LaH10 ± δ with dimensions up to 10 × 20 μm2 by laser heating a thin La flake and ammonia borane at ∼ 1700 K in a symmetric diamond anvil cell under the pressure of 165 GPa. The superconducting transition at T c ≈ 250 K was confirmed through resistance measurements under various magnetic fields. Our method will facilitate explorations of near-room-temperature superconductors among metal superhydrides.

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The lutetium dihydride LuH2 is stable at ambient conditions. Here we show that its color undergoes sequential changes from dark blue at ambient pressure to pink at ~2.2 GPa and then to bright red at ~4 GPa upon compression in a diamond anvil cell. Such a pressure-induced color change in LuH2 is reversible and it is very similar to that recently reported in the N-doped lutetium hydride [Nature 615, 244 (2023)]. However, our preliminary resistance measurements on LuH2 under pressures up to ~7 GPa evidenced no superconductivity down to 1.5 K.

We report a comprehensive high-pressure study on the monoclinic TlFeSe2 single crystal, which is an antiferromagnetic insulator with quasi-one-dimensional crystal structure at ambient pressure. It is found that TlFeSe2 undergoes a pressure-induced structural transformation from the monoclinic phase to an orthorhombic structure above P c ≈ 13 GPa, accompanied with a large volume collapse of ΔV/V 0 = 8.3%. In the low-pressure monoclinic phase, the insulating state is easily metallized at pressures above 2 GPa; while possible superconductivity with T c onset ∼ 2 K is found to emerge above 30 GPa in the high-pressure phase. Such a great tunability of TlFeSe2 under pressure indicates that the ternary AFeSe2 system (A = Tl, K, Cs, Rb) should be taken as an important platform for explorations of interesting phenomena such as insulator-metal transition, dimensionality crossover, and superconductivity.

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Among the metal hydrides, Th4H15 is the first reported superconductor with a relatively high T c ≈ 8 K at ambient pressure. Here we report on the synthesis and characterization of a low-T c superconducting modification of Th4H15, which is obtained via hydrogenating Th metal at 5 GPa and 800 °C by using the ammonia borane as the hydrogen source. Measurements of resistivity, magnetic susceptibility, and specific heat confirm that the obtained Th4H15 sample shows a bulk superconducting transition at T c ≈ 6 K, which is about 2 K lower than that reported previously. Various characteristic superconducting parameters have been extracted for this compound and unusual lattice dynamics were evidenced from the specific-heat analysis.