Linear magnetoresistance and structural distortion in layered SrCu_(4-x)P_(2) single crystals

We report a systematic study on layered metal SrCu_(4-x)P_(2) single crystals via transport, magnetization, thermodynamic measurements and structural characterization. We find that the crystals show large linear magnetoresistance without any sign of saturation with a magnetic field up to 30T. We also observe a phase transition with significant anomalies in resistivity and heat capacity at T_(p)~140 K. Thermal expansion measurement reveals a subtle lattice parameter variation near Tp, i.e.,?L_(c)/L_(c)~0.062%. The structural characterization confines that there is no structure transition below and above T_(p). All these results suggest that the nonmagnetic transition of SrCu_(4-x)P_(2) could be associated with structural distortion.

Observation of Charge Density Wave in Layered Hexagonal Cu1.89Te Single Crystal

We report comprehensive transport, electron microscopy and Raman spectroscopy studies on transition-metal chalcogenides Cu1.89Te single crystals. The metallic Cu1.89Te displays successive metal-semiconductor transitions at low temperatures and almost ideal linear MR when magnetic field up to 33 T. Through the electron diffraction patterns, the stable room-temperature phase is identified as a 3 × 3 × 2 modulated superstructure based on the Nowotny hexagonal structure. The superlattice spots of transmission electron microscopy and scanning tunneling microscopy clearly show the structural transitions from the room-temperature commensurate Ⅰ phase, named as C-Ⅰ phase, to the low temperature commensurate Ⅱ(C-Ⅱ) phase. All the results can be understood in terms of charge density wave(CDW) instability, yielding intuitive evidences for the CDW formations in Cu1.89Te. The additional Raman modes below room temperature further reveal that the zone-folded phonon modes may play an important role on the CDW transitions. Our research sheds light on the novel electron features of Cu1.89Te at low temperature, and may provide potential applications for future nano-devices.

Ultra-broadband,fast,and polarization-sensitive photoresponse of low-symmetry 2D NdSb_(2)

Broadband photodetectors with polarization-sensitive ability have received extraordinary attention for modern optoelectronic devices.Ideal photodetectors should possess high responsivity,fast response,and good stability,which are rare to meet at the same time in one low-symmetric two-dimentional(2D)material.In this work,neodymium diantimonides(RSb_(2)),a member of light rare-earth diantimonides RSb_(2)(R=La–Nd,Sm)with low-symmetry structure,is introduced as a fascinating highly anisotropic 2D material for broadband detection(532 nm to 4μm).The photodetector exhibits a responsivity of 0.49 mA·W^(−1)with 15μs response time at 532 nm and highly stable performance under ambient conditions over 8 months.Furthermore,we identify the polarization-sensitive photoresponse of the detector and demonstrate a high anisotropic factor~1.6.In addition,strong inplane anisotropy is revealed by anisotropic phonon response and the photodetection mechanism is investigated by scanning photocurrent microscopy measurements.This pioneer work on RSb_(2)paves the way for further exploration of 2D RSb_(2)for high performance polarized photodetectors with fast photothermoelectric response.