409 research outputs found
Large magnetoresistance in the magnetically ordered state as well as in the paramagnetic state near 300 K in an intermetallic compound,Gd7Rh3
We report the response of electrical resistivity to the application of
magnetic fields (H) up to 140 kOe in the temperature interval 1.8-300 K for the
compound, Gd7Rh3, ordering antiferromagnetically below 150 K. We find that
there is an unusually large decrease of for moderate values of H in the
close vicinity of room temperature uncharacteristic of paramagnets, with the
magnitude of the magnetoresistance increasing with decreasing temperature as
though the spin-order contribution to is temperature dependent. In
addition, this compound exhibits giant magnetoresistance behaviour at rather
high temperatures (above 77 K) in the magnetically ordered state due to a
metamagnetic transition.Comment: Europhyics Letters, in pres
Field-induced first-order magnetic phase transition in an intermetallic compound, Nd7Rh3: Evidence for kinetic-hindrance, phase co-existence and percolative conduction
The compound, Nd7Rh3, crystallizing in Th7Fe3-type hexagonal structure, was
previously known to exhibit two magnetic transitions, one at 32 K and the other
at 10 K (in zero magnetic field). Here, we report the existence of a
field-induced first-order antiferromagnetic to ferromagnetic transition at 1.8
K in this compound. On the basis of the measurements of isothermal
magnetization and magnetoresistance, we provide evidence for the occurence of
kinetic-hindrance, proposed in the literature, resulting in phase co-existence
(super-cooled ferromagnetic + antifferomagnetic) and percolative electrical
conduction in this stoichiometric intermetallic compound. A point of emphasis,
as inferred from ac susceptibility data, is that such a co-existing phase is
different from spin-glasses, thereby clarifying a question raised in the field
of phase-separation.Comment: A Shortened version will appear in print in PRB (Rapid Comm). Phys.
Rev. B (Rapid Comm), in pres
Large magnetoresistance anomalies in Dy7Rh3
The compound Dy7Rh3 ordering antiferromagnetically below (TN=) 59 K has been
known to exhibit a temperature (T) dependent electrical resistivity (rho)
behavior in the paramagnetic state unusual for intermetallic compounds in the
sense that there is a broad peak in rho(T) in the paramagnetic state (around
130 K) as though there is a semi-conductor to metal transition. In addition,
there is an upturn below T_N due to magnetic super-zone gap effects. Here we
report the influence of external magnetic field (H) on the rho(T) behavior of
this compound below 300 K. The rise of rho(T) found below TN could be
suppressed at very high fields (>> 60 kOe), thus resulting in a very large
magnetoresistance (MR) in the magnetically ordered state. The most notable
finding is that the magnitude of MR is large for moderate applications of H
(say 80 kOe) in a temperature range far above T_N as well, which is untypical
of intermetallic compounds. Thus, this compound is characterized by large MR
anomalies in the entire T range of investigation.Comment: IOP Selec
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