Search

Finding promising materials that show large thermoelectricity at low temperatures is crucial for low-temperature refrigeration applications. Here, we report a significantly large thermoelectric power factor ( PF) up to 50 μW cm−1 K−2 at an extremely low temperature of ∼8 K in a quasi-one-dimensional (Q1D) antiferromagnet KMn6Bi5, in which highly electrical conductivity and dramatic enhancement of Seebeck coefficient may favor its occurrence. In addition, a giant Nernst signal has also been detected with a maximum value of 24 μV K−1 T−1 at ∼5 K. All these intriguing characteristics observed in KMn6Bi5 can be attributed to the manifestation of the unusually strong coupling among spin, charge, lattice, and one dimensionality in KMn6Bi5. Our findings provide fundamental insight into the thermal transport in Q1D antiferromagnets and should stimulate further experimental exploration of thermal transport in such Q1D family for possible thermoelectric applications at extremely low temperatures.

Magnetic Weyl semimetals (MWSM) have attracted significant attention due to their intriguing physical properties and potential applications in spin-electronic devices. Here we report the characterization of NdAlSi including transport, magnetization, and heat capacity on single crystals, as well as band structure calculation. It is a newly proposed MWSM candidate which breaks both time-reversal and spacial inversion symmetries. A temperature-magnetic field phase diagram is experimentally established. Remarkably, on the angular magnetoresistance (AMR), a two-fold symmetric sharp peak instead of a smooth variation is observed in the field-induced ferrimagnetic phase. We argue that the tunability of both the topological and magnetic properties in NdAlSi is crucial for realizing such a behavior. Our results indicate that 4f-electron-based MWSM can provide a unique platform to explore new and intriguing quantum phenomena arising from the interaction between magnetism and topology., 24 pages, 12 figures