High pressure synthesis and characterization of the pyrochlore Dy2Pt2O7:A new spin ice material

The cubic pyrochlore Dy2Pt2O7 was synthesized under 4 GPa and 1000℃ and its magnetic and thermodynamic properties were characterized by DC and AC magnetic susceptibility and specific heat down to 0.1 K.We found that Dy2Pt2O7 does not form long-range magnetic order,but displays characteristics of canonical spin ice such as Dy2Pt2O7,including(1)a large effective moment 9.64μB close to the theoretical value and a small positive Curie-Weiss temperatureθCW=+0.77 K signaling a dominant ferromagnetic interaction among the Ising spins;(2)a saturation moment ~4.5μB being half of the total moment due to the local<111>Ising anisotropy;(3)thermally activated spin relaxation behaviors in the low(~1 K)and high(~20 K)temperature regions with different energy barriers and characteristic relaxation time;and most importantly,(4)the presence of a residual entropy close to Pauling’s estimation for water ice.

Point-contact spectroscopy on antiferromagnetic Kondo semiconductors Ce𝑇T2Al10 (T= Ru and Os)

We have carried out point-contact spectroscopy(PCS)measurements on one family of antiferromagnetic Kondo semiconductor CeT2Al10(T=Ru and Os)with a Neel temperature´TN∼27.5 and 28.5 K,respectively.Their PCS conductance curves both exhibit a characteristic coherent double-peak-structure at temperatures below TN,signaling an AFM gap around the Fermi surface.The temperature dependent AFM gap∆1 follows a Bardeen-Cooper-Schrieffer(BCS)-like mean-field behavior with a moderate gap anisotropy for PCS along different crystal axes.Another asymmetric gap-like feature is observed for both compounds at temperatures far below TN,which is consistent with opening of a new hybridization gap∆h inside the long-range ordered AFM state.Our results suggest a common itinerant nature of the anomalous AFM ordering,constraining theoretical models to explain the AFM origin in CeRu2Al10 and CeOs2Al10.

Electric and thermal transport properties of topological insulator candidate LiMgBi

We report the transport properties of a topological insulator candidate,LiMgBi.The electric resistivity of the title compound exhibits a metal-to-semiconductor-like transition at around 160 K and tends to saturation below 50 K.At low temperatures,the magnetoresistance is up to~260%at 9 T and a clear weak antilocalization effect is observed in the low magnetic-field region.The Hall measurement reveals that LiMgBi is a multiband system,where hole-type carriers(nh~1018 cm^(-3))play a major role in the transport process.Remarkably,LiMgBi possess a large Seebeck coefficient(~440μV/K)and a moderate thermal conductivity at room temperature,which indicate that LiMgBi is a promising candidate in thermoelectric applications.

Microfacies and paleoenvironment of microbialites of the Cambrian(Stage 4)Qingxudong Formation in the Huayuan area,northwestern Hunan Province,southern China

After the extinction of Archaeocyatha(sponges),microbial bioherms were well developed in the lower Cambrian of the Yangtze cratonic basin,especially in the Qingxudong Formation(Cambrian(Stage 4))of the Huayuan area,northwestern Hunan Province,southern China.Herein,four sections from this area were chosen for investigating and analyzing their microfacies and depositional environment.Twelve microfacies types were recognized through petrographic analysis of textural attributes and calcimicrobes(including Epiphyton,Renalcis,Girvanella and Kenella),respectively as:laminated calcareous mudstone(MF1),algal wackestone(MF2),intraclastic grainstone(MF3),algal intrasparrudite(MF4),oolitic algal intrasparrudite(MF5),sparry oolitic grainstone(MF6),Epiphyton framestone(MF7),Renalcis bafflestone(MF8),Kenella bafflestone(MF9),Girvanella boundstone(MF10),thrombolitic boundstone(MF11),and dolomite(MF12).These microfacies represent four major depositional environments:carbonate ramp,carbonate platform,slope and tidal flat.Calcimicrobes played an important role in the transition from carbonate ramp to platform,while the evolution from ramp to tidal flat must be ascribed to sea-level fall during the Cambrian Age 4.