ABSTRACT
Fe-doped ZnO nanorods were synthesized by solvothermal method with Fe concentration of 2%, 5% and 10%, respectively. The morphological and structural properties of the Fe-doped ZnO nanorods were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) technique, respectively. The presence of Fe doping with different concentration was confirmed by X-ray fluorescence (XRF) spectroscopy. For largest doping concentration of Fe, the optical band gap of ZnO was found to shift considerably about 25% to lower energies than that of the pristine ZnO. Furthermore the magnetic behavior was investigated on doped and undoped ZnO samples at room temperature as well as at low temperature. We found that these nanorods do not exhibit room temperature ferromagnetism. Instead a superparamagnetic-type behavior is observed for all the concentration with the blocking temperature in the range 13-35 K.
ABSTRACT
We present magnetic characterization of a binary rare-earth intermetallic compound Er(5)Si(3), crystallizing in Mn(5)Si(3)-type hexagonal structure, through magnetization, heat capacity, electrical resistivity and magnetoresistance measurements. Our investigations confirm that the compound exhibits two magnetic transitions with decreasing temperature, the first one at 35 K and the second one at 15 K. The present results reveal that the second magnetic transition is a disorder-broadened first-order transition, as shown by thermal hysteresis in the measured data. Another important finding is that, below 15 K, there is a magnetic-field-induced transition with a hysteretic effect with the electrical resistance getting unusually enhanced at this transition and the magnetoresistance is found to exhibit intriguing magnetic-field dependence, indicating novel magnetic phase coexistence phenomenon. It thus appears that this compound is characterized by interesting magnetic anomalies in the temperature-magnetic-field phase diagram.
Subject(s)
Electric Impedance , Erbium/chemistry , Magnetic Fields , Manganese/chemistry , Silicon Compounds/chemistry , TemperatureABSTRACT
Despite intense research in the field of strongly correlated electron behavior for the past few decades, there has been very little effort to understand this phenomenon in nanoparticles of the Kondo lattices. In this paper, we review the results of our investigation on the fine particles (<<1 µm) of some of the alloys obtained by high-energy ball-milling, to bring out that this synthetic method paves a way to study strong electron correlations in nanocrystals of such alloys. We primarily focus on the alloys of the series CeRu(2 - x)Rh(x)Si2, lying at different positions in Doniach's magnetic phase diagram. While CeRu2Si2, a bulk paramagnet, appears to become magnetic (of a glassy type) below about 8 K in fine particle form, in CeRh2Si2, an antiferromagnet (T(N) = 36 K) in bulk form, magnetism is destroyed (at least down to 0.5 K) in fine particles. In the alloy CeRu0.8Rh1.2Si2, at the quantum critical point known to exhibit non-Fermi liquid behavior in the bulk form, no long range magnetic ordering is found.
ABSTRACT
We have investigated the magnetic behavior of the nanocrystalline form of a well-known Laves phase compound, ErCo(2)-the bulk form of which has been known to undergo an interesting first-order ferrimagnetic ordering near 32 K-synthesized by high-energy ball-milling. It is found that, in these nanocrystallites, Co exhibits ferromagnetic order at room temperature, as inferred from the magnetization data. However, the magnetic transition temperature for the Er sub-lattice remains essentially unaffected suggesting the (Er)4f-Co(3d) coupling is weak on Er magnetism. The net magnetic moment as measured at high fields, for example at 120 kOe, is significantly reduced with respect to that for the bulk in the ferrimagnetically ordered state and possible reasons are outlined for this. We have also compared the magnetocaloric behavior for the bulk and for nanoparticles.
