Magneto-optical behavior of EuIn(2)P(2)

We report results of a magneto-optical investigation of the Zintl-phase compound EuIn(2)P(2). The compound orders magnetically at T(C)=24 K and exhibits concomitant large magnetoresistance effects. For T <= 50 K and increasing magnetic fields we observe a transfer of spectral weight in sigma(1)(omega) 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.