Magnetothermal conductivity of Ta2NiSe5 at low temperatures

Ta2NiSe5 (TNS) has been intensely studied due to its supposed proximity to the coveted excitonic insulator state. While a variety of experimental techniques such as Raman spectroscopy, NMR/Knight shift, and transport have lended support to the excitonic insulator claim, there have since been recent ARPES and diffuse X-ray scattering results that suggest the features of TNS are due to strong electron-lattice coupling and lattice fluctuations. Nonetheless, the bulk of these studies focus on the transition at Tc = 329 K; few studies have explored the low temperature behavior of this material. Several studies have noted certain features below 100 K, such as an upturn in magnetic susceptibility, suppressed electronic activation energy, and a suppression of the thermopower. It is not yet clear whether these features are intrinsic to the sample or due to impurities, nor is it clear whether they are related to any exciton physics. Here, we present low-temperature magnetothermal conductivity measurements on TNS in order to clarify the quasiparticle behavior as well as the underlying cause of these features.