اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدHydrostatic pressure effects on the electrical transport properties of Pr0.5Sr0.5MnO3
167
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We studied single-crystalline Pr0.5Sr0.5MnO3 by means of measurements of magnetic susceptibility and specific heat at ambient pressure (P), and electrical resistivity (r) in hydrostatic pressures up to 2 GPa. This material displays ferromagnetic (FM) order, with Curie temperature TC ~ 255 K. A crystallographic transformation from I4/mcm to Fmmm is accompanied by the onset of antiferromagnetism (AFM), with Neel temperature TN ~ 161 K. The effect of pressure is to lower TC, and raise TN at the approximate rates of -3.2 K/GPa, and 14.2 K/GPa, respectively. Although the value of TN increases with P, due to the enhancement of the superexchange interactions, the AFM-Fmmm state is progressively suppressed, as pressure stabilizes the FM-I4/mcm phase to lower temperatures. The r vs T data suggest that the AFM phase should be completely suppressed near 2.4 GPa.
قيم البحث
اقرأ أيضاً
We studied the evolution of superconductivity (sc) and antiferromagnetism (afm) in the heavy fermion compound CePt_3Si with hydrostatic pressure. We present a pressure-temperature phase diagram established by electrical transport measurements. Pressu
re shifts the superconducting transition temperature, T_c, to lower temperatures. Antiferromagnetism is suppressed at a critical pressure P_c=0.5 GPa.
The low-temperature magnetic properties of tcr{polycrystalline} Na$_2$IrO$_3$, a candidate material for the realization of a quantum spin-liquid state, were investigated by means of muon-spin relaxation and nuclear magnetic resonance methods under ch
emical and hydrostatic pressure. The Li-for-Na chemical substitution promotes an inhomogeneous magnetic order, whereas hydrostatic pressure (up to 3.9,GPa) results in an enhancement of the ordering temperature $T_mathrm{N}$. In the first case, the inhomogeneous magnetic order suggests either short- or long-range correlations of broadly distributed $j=,$textonehalf Ir$^{4+}$ magnetic moments, reflecting local disorder. The increase of $T_mathrm{N}$ under applied pressure points at an increased strength of three dimensional interactions arising from interlayer compression.
We have investigated the temperature dependence of the magnetic susceptibility $chi(T)$ of rare-earth cobaltites RCoO$_3$ (R= La, Pr, Nd, Sm, Eu) in the temperature range $4.2-300$ K and also the influence of hydrostatic pressure up to 2 kbar on thei
r susceptibility at fixed temperatures $T=78 $ and 300 K. The specific dependence $chi(T)$ observed in LaCoO$_3$ and the anomalously large pressure effect (d ln $chi$/d$Psim -100$ Mbar$^{-1}$ for $T = 78$ K) are analyzed in the framework of a two-level model with energy levels difference $Delta$. The ground state of the system is assumed to be nonmagnetic with the zero spin of Co$^{3+}$ ions, and magnetism at a finite temperature is determined by the excited magnetic spin state. The results of the analysis, supplemented by theoretical calculations of the electronic structure of LaCoO$_3$, indicate a significant increase in $Delta$ with a decrease in the unit cell volume under the hydrostatic pressure. In the series of RCoO$_3$ (R= Pr, Nd, Sm, Eu) compounds, the volume of crystal cell decreases monotonically due to a decrease in the radius of R$^{3+}$ ions. This leads to an increase in the relative energy $Delta$ of the excited state (the chemical pressure effect), which manifests itself in a decrease in the contribution of cobalt ions to the magnetic susceptibility at a fixed temperature, and also in a decrease in the hydrostatic pressure effect on the susceptibility of RCoO$_3$ compounds, which we have observed at $T=300$ K.
The pressure-induced changes in the temperature-dependent thermopower S(T) and electrical resistivity rho(T) of CeRu_2Ge_2 are described within the single-site Anderson model. The Ce-ions are treated as impurities and the coherent scattering on diffe
rent Ce-sites is neglected. Changing the hybridisation Gamma between the 4f-states and the conduction band accounts for the pressure effect. The transport coefficients are calculated in the non-crossing approximation above the phase boundary line. The theoretical S(T) and rho(T) curves show many features of the experimental data. The seemingly complicated temperature dependence of S(T) and rho(T), and their evolution as a function of pressure, is related to the crossovers between various fixed points of the model.
We present the first study of a magnetic quantum phase transition in the itinerant-electron ferromagnet Ni3Al at high pressures. Electrical resistivity measurements in a diamond anvil cell at hydrostatic pressures up to 100 kbar and temperatures as l
ow as 50 mK indicate that the Curie temperature collapses towards absolute zero at a critical pressure pc=82(2) kbar. Over wide ranges in pressure and temperature, both in the ferromagnetic and paramagnetic states, the temperature variation of the resistivity is found to deviate from the conventional Fermi-liquid form. We consider the extent to which this deviation can be understood in terms of a mean-field model of enhanced spin fluctuations on the border of ferromagnetism in three dimensions.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
