High-field magnetization and magnetoresistance ofLa0.5Sr1.5MnO

Abstract

͑Received 21 December 1998͒Measurements of magnetization and magnetoresistance have been made for crystals of La 0.5 Sr 1.5 MnO 4 with use of pulsed magnetic fields up to 40 T. Application of high magnetic field causes metamagnetic transitions below 217 K and concomitantly the colossal magnetoresistance effect. At low magnetic fields, change of resistivity is expressed well by a formula for hopping conduction whose activation energy decreases in proportion to the square of magnetization. In high fields, temperature dependence of resistivity cannot be explained by a simple extrapolation from the low-field region. The transition from the low-field regime to the high-field one is ascribed to the magnetic-field induced melting of the charge and orbital ordering, as evidenced by the metamagnetic transition.

Crystal and magnetic structure ofLa1−xSr1+xMnO4: Role of the orbital degree of freedom

“…The anomalies in the thermal expansion suggesting a rearrangement of the orbital occupation induced by the magnetic interaction resemble recent observations on LaTiO 3 26,27 and on Ca 2 RuO 4 . 28 In these compounds, one finds an enhancement of an octahedron distortion upon approach of the Néel order.…”

“…Like the perovskite LaMnO 3 , La 1.0 Sr 1.0 MnO 4 exhibits an antiferromagnetic order. Kawano et al report a small ordered moment of only 0.8 µ B 9 compared to the value of 3.87(3) observed in LaMnO 3 .…”

Electronic transport in ferromagneticLa1−xSrxMnOBebenin1, Zainullina2, Mashkautsan3 et al. 2004Phys. Rev. B431120View full textAdd to dashboardCite

“…Tokunaga et al 47 noted that the formula ͑4͒ may be applied to hopping conductivity although the preexponential factor is not of course min Ϫ1 . They found that the change of resistivity in La 1/2 Sr 3/2 MnO 4 agrees well with the simple model of hopping conduction with activation energy varying as m 2 if mр0.7.…”

Melting of magnetic correlations in charge-orbital orderedLa1/2Sr3/2MnO4Senff1, Schumann2, Benomar3 et al. 2008Phys. Rev. B232280View full textAdd to dashboardCite

“…9,[33][34][35][36] Magnetic ordering of the CE type occurs below T N = 110 K. 9 Compared to the perovskite manganites, the COO state is exceptionally stable in La 1/2 Sr 3/2 MnO 4 and only very high fields of the order of 30 T can melt the ordered state, implying negative magnetoresistance effects. 37 Good metallic properties are, however, never achieved in the single-layered manganites La 1−x Sr 1+x MnO 4 neither by magnetic field nor by doping. 38,39 In a recent work, we have studied the magnetic excitation spectrum of the CE-type ordering in La 1/2 Sr 3/2 MnO 4 at low temperatures.…”