UC Irvine

We report results of a magneto-optical investigation of the Zintl-phase compound EuIn2 P2. The compound orders magnetically at TC =24 K and exhibits concomitant large magnetoresistance effects. For T≤50 K and increasing magnetic fields we observe a transfer of spectral weight in σ1 (ω) from energies above 1 eV into the low-energy metallic component as well as into a midinfrared signal centered at about 600 cm-1. This latter absorption is reminiscent to what has been seen in a large variety of so-called Kondo materials and ascribed to excitations across the hybridization gap. The observed gain of Drude weight upon increasing magnetic field suggests an enhancement of the itinerant charge-carrier concentration due to the increasing magnetization, a phenomenon that was previously observed in other compounds that exhibit colossal magnetoresistive effects. © 2008 The American Physical Society.