Sujata Patil

Ce3Cu3Sb4: The first Ce-based semiconducting ferromagnet

Abstract We report here experimental investigations on Ce 3 Cu 3 Sb 4 and Gd 3 Cu 3 Sb 4 which are members of a new series reported by us. Ce 3 Cu 3 Sb 4 is found to be a semiconducting ferromagnet with T m = 10 K and hence unique as no other Ce -based system exhibits these properties. The isostructural Gd 3 Cu 3 Sb 4 is a metallic antiferromagnet with T N = 12K. The ferromagnetic ordering temperature T m of Ce 3 Cu 3 Sb 4 is rather high and could be due to p - f hybridization.

Magnetism and mixed valence in some R2M3X5 compounds: R = Ce, Eu; M = d metals, X = Si, Ge

Abstract Lattice parameters, magnetic susceptibility and LIII edge measurements have been performed as a function of temperature on a number of new materials of the chemical composition R2M3X5 (R = Ce, Eu; M = Ni, Rh, Pd, Ir; X = Si, Ge). Valence instabilities have been observed in Ce2Rh3Si5 and Ce2Ir3Si5. Eu2Ni3Si5 is mixed valent as revealed by LIII edge and Mossbauer measurements; and the valence of Eu varies between 2.75 and 2.60 in the temperature range 10–300 K. Other materials show magnetic ordering.

Ni3d-Gd4f correlation effects on the magnetic behaviour of GdNi

Abstract The results of magnetization and heat-capacity measurements on the alloys, Gd1−xYxNi(x = 0.0,0.25,0.5,0.75 and 0.9) are reported. The data suggest that there is a Gd induced magnetic moment on Ni, which may in turn enhance Gdue5f8Gd exchange interaction strength in GdNi. The induced moment (on Ni) apparently exhibits itinerant ferromagnetism in the magnetically ordered state of GdNi.

151Eu Mössbauer studies in EuNiSi2 - A new mixed valence system - and in EuNi2Si2 and EuNiSi3

151Eu Mossbauer measurements are reported on a new mixed valence (MV) material EuNiSi2. Isomer shift varies from -2.5 mm/s (300 K to -0.6 mm/s (20 K). Our studies of EuNi2Si2 and EuNiSi3 show that in these compounds Eu is present in only one valence state, 3+ and 2+, respectively.

Ce3Rh3Sb4 : An antiferromagnetic Kondo lattice

Abstract Magnetic susceptibility, d.c. electrical resistivity and magnetoresistivity measurements on a new intermetallic compound Ce 3 Rh 3 Sb 4 have been carried out in the temperature range 2 K to 300 K. The experimental investigations show that Ce 3 Rh 3 Sb 4 orders antiferromagnetically at 22 K. Magnetic resistivity, ρ m shows a broad maximum at about 50 K and -ln( T ) dependence in the high temperature region. These experimental investigations indicate a competition of Kondo effect and magnetic ordering with the influence of crystal field effect on the 4f moments.

Studies of structural, magnetic and transport properties of a new series R/sub 3/Cu/sub 3/Sb/sub 4/ (R=La, Ce, Pr, Gd)

We report here the synthesis of a new series of materials, R/sub 3/Cu/sub 3/Sb/sub 4/ (R=La, Ce, Pr and Gd) and the preliminary results of their magnetic and transport properties. >

Magnetoresistance of Ce3Cu3Sb4: Ferromagnetic semiconductor (abstract)

Ferromagnetic semiconductors are an interesting class of materials. The first one, CrBr3 was discovered only in 1960. Magnetic semiconductors usually show a prominent peak in the resistivity and a very large negative magnetoresistance (MR) in the vicinity of Tc, which is not well understood. Recently, we have reported Ce3Cu3Sb4 to be a ferromagnetic semiconductor with a Tc of 10 K.1 To our knowledge, this is the first Ce system of this type and is a further addition to the rich varieties of ground states exhibited by Ce systems. Here, we report the MR studies on Ce3Cu3Sb4 in magnetic fields up to 8 T in the temperature range 4.2–300 K. The resistivity of Ce3Cu3Sb4 shows a rise with decrease in temperature from 300 K exhibiting a peak at 19 K followed by a drastic fall at low temperatures. An activation type fit to the data gives a band-gap energy of 84 K. The resistivity peak is broadened considerably in a field of 8 T and the peak is found to shift to higher temperatures by about 10 K. The MR is small an...

Resistivity and magnetic susceptibility of R3Au3Sb4 (R Nd, Gd, Tb and Er)

Abstract Resistivity and magnetic susceptibility of R3Au3Sb4 (R ue5fb Nd, Gd, Tb, and Er) have been measured in the temperature range 5–300 K. Nd-, Gd- and Tb-based compounds are semiconducting throughout this temperature interval. Er3Au3Sb4 is semiconducting at low temperatures but metallic at high temperatures. No magnetic transition is observed in Nd, Tb and Er samples down to 5 K.

Crystallographic and Magnetic Investigations in the Pseudoternary Alloy System Ce(Ir1−xRhx)2Si2

Ce-based systems of ThCr2Si2 type structure exhibit ground state properties with remarkable features : CeCU2Si2 is a heavy fermion superconductor, CeRu2Si2 is a dense Kondo lattice system, CePd2Si2 is an antiferromagnetic system (TN = 10K) with high Curie-Weiss temperature. CeRh2Si2 undergoes an antiferromagnetic ordering at rather high temperature (Tnj = 39K) [1,2]. Ir-based system REIr2Si2 (RE = rare earth) exhibit interesting polymorphic transormations [3]. Rapidly cooled samples, for instance, of LaIr2Si2 crystallize in the CaBe2Geo type primitive tetragonal structure (P) and slow cooled samples crystallize in the bodycentered ThCr2Si2 type structure (I). The two polymorphic forms of CeIr2Si2 have different mixed valence behaviour [3]. In view of the striking difference in the crystallographic and magnetic properties of CeIr2Si2 and CeRh2Si2, pseudo-ternary alloys are ideally suited to study the evolution or the magnetic ground state from a mixed valent ground state. It was also considered to be of interest to examine the influence of Rh on the polymorphic properties of CeIr2Si2.