Enhanced conduction band density of states in intermetallic EuTSi$_3$ (T=Rh, Ir)

TL;DR

This study reveals that EuRhSi$_3$ and EuIrSi$_3$ have enhanced electronic density of states at the Fermi level, leading to unusual magnetic and transport properties, including giant magnetoresistance and large exchange interactions.

Contribution

The paper demonstrates that the electronic density of states at the Fermi level is strongly enhanced in EuRhSi$_3$ and EuIrSi$_3$, significantly affecting their magnetic and transport behaviors.

Findings

Enhanced density of states at the Fermi level in EuRhSi$_3$ and EuIrSi$_3$

Giant magnetoresistance exceeding 600% in EuIrSi$_3$

Large spin-flop field and spin-wave gap values

Abstract

We report on the physical properties of single crystalline EuRhSi$_3$ and polycrystalline EuIrSi$_3$, inferred from magnetisation, electrical transport, heat capacity and $^{151}$Eu M\"ossbauer spectroscopy. These previously known compounds crystallise in the tetragonal BaNiSn$_3$-type structure. The single crystal magnetisation in EuRhSi$_3$ has a strongly anisotropic behaviour at 2 K with a spin-flop field of 13 T, and we present a model of these magnetic properties which allows the exchange constants to be determined. In both compounds, specific heat shows the presence of a cascade of two close transitions near 50 K, and the $^{151}$Eu M\"ossbauer spectra demonstrate that the intermediate phase has an incommensurate amplitude modulated structure. We find anomalously large values, with respect to other members of the series, for the RKKY N\'eel temperature, for the spin-flop field (13 T), for the spin-wave gap ($\simeq$ 20-25 K) inferred from both resistivity and specific heat data, for the spin-disorder resistivity in EuRhSi$_3$ ($\simeq 35$ $\mu$Ohm.cm) and for the saturated hyperfine field (52 T). We show that all these quantities depend on the electronic density of states at the Fermi level, implying that the latter must be strongly enhanced in these two materials. EuIrSi$_3$ exhibits a giant magnetoresistance ratio, with values exceeding 600 % at 2 K in a field of 14 T.