title: Magnetic behavior of bulk and fine particles of RCr2Si2C (R = La, Ce) compounds: possible magnetic ordering from Cr.
abstract: The magnetic behavior of the quaternary compounds, RCr(2)Si(2)C (R = La, Ce), has been investigated by magnetization (M) and heat-capacity (C) measurements (1.8-300 K) in the bulk polycrystals and nano forms (<1 µm) obtained by high-energy balling. Our finding is that Cr appears to exhibit magnetic ordering of an itinerant type at low temperatures (<20 K) in the bulk form, as inferred from a combined look at all the data. The magnetic ordering gets gradually suppressed with increasing milling time. Evidence for a mixed-valence state of Ce for the bulk form is obtained from the tendency of magnetic susceptibility to exhibit a maximum above 300 K. However, this feature vanishes in the nano form, which exhibits a Curie-Weiss behavior above 200 K as though Ce tends towards trivalency in these fine particles; in addition, there is a weak upturn in C/T below 10 K in the bulk, which becomes very prominent in the milled Ce-based specimens at lower temperatures, as though heavy-fermion behavior gets stronger in smaller particles.
authors.affiliation: Tata Institute of Fundamental Research, Colaba, Mumbai, India.
authors.forename: K
authors.initials: K
authors.lastname: Mukherjee
authors.forename: Kartik K
authors.initials: KK
authors.lastname: Iyer
authors.forename: E V
authors.initials: EV
authors.lastname: Sampathkumaran