Thermal hysteretic behavior and negative magnetoresistance in an unusual charge-density-wave material EuTe4

TL;DR

EuTe4 is a novel van der Waals material exhibiting a high-temperature charge-density wave with significant thermal hysteresis and negative magnetoresistance, studied through ARPES, STM, and magnetotransport measurements.

Contribution

This work provides the first detailed electronic and magnetic characterization of EuTe4, revealing its high-temperature CDW, surface domain structures, and magnetic effects on transport properties.

Findings

CDW gap persists up to 400 K

Thermal hysteresis in resistivity and ARPES intensity

Large negative magnetoresistance at low temperatures

Abstract

EuTe4 is a newly-discovered van der Waals material exhibiting a novel charge-density wave (CDW) with a large thermal hysteresis in the resistivity and CDW gap. In this work, we systematically study the electronic structure and transport properties of EuTe4 using high-resolution angle-resolved photoemission spectroscopy (ARPES), magnetoresistance measurements, and scanning tunneling microscopy (STM). We observe a CDW gap of about 200 meV at low temperatures that persists up to 400 K, suggesting that the CDW transition occurs at a much higher temperature. We observe a large thermal hysteretic behavior of the ARPES intensity near the Fermi level, consistent with the resistivity measurement. The hysteresis in the resistivity measurement does not change under a magnetic field up to 7 T, excluding the thermal magnetic hysteresis mechanism. Instead, the surface topography measured with STM shows surface domains with different CDW trimerization directions, which may be important for the thermal hysteretic behavior of EuTe4. Interestingly, we observe a large negative magnetoresistance at low temperatures that can be associated with the canting of magnetically ordered Eu spins. Our work shed light on the understanding of magnetic, transport, and electronic properties of EuTe4.