Temperature dependent memory effects in the bilayer manganite(La0.4Pr0.6)<

Abstract

We report on the low-temperature resistance and magnetization of a single crystal of the bilayer manganite (La 0.4 Pr 0.6 ) 1.2 Sr 1.8 Mn 2 O 7 . In zero field the sample is an insulator at all temperatures while at fields larger than 3 T a transition to a ferromagnetic metallic state is observed. Below 50 K the sample shows a pronounced memory effect, in which both resistivity and magnetization become dependent on the magnetic history and clearly demonstrate hysteretic behavior. At these low temperatures a difference in zero-field resistivity before and after magnetization of six orders of magnitude has been measured. The relaxation of the memory effect follows a stretched exponential function with a characteristic decay time of 5 hours at 10 K, which decreases to less than 1 ms above 40 K. These low-temperature properties can be related to magnetostriction data, indicating the presence of a field-induced change in the orbital occupancy of the e g electrons of Mn 3ϩ .

Magneto-optical investigation of the field-induced spin-glass-insulator to ferromagnetic-metal transition in the bilayer manganite(La0.4Pr0.6)1.2Cao1, Haraldsen2, Rai3 et al. 2006Phys. Rev. BSelf Cite

“…51 Above 50 K, relaxation effects are more rapid. 29 Here, the phase diagram from both optics (which measures the microscopic nature of the charge degrees of freedom) and magnetization are in good agreement, although the boundary becomes more diffuse with increasing temperature (inset, Fig. 6(a)).…”

“…57 For comparison, we also plotted several points determined from selected resistivity, magnetization, and magnetostriction measurements. 29,31,51 Magnetization measurements indicate two boundaries at ∼2 and 5 T below 50 K, perhaps due to domain rotation. 51 Above 50 K, relaxation effects are more rapid.…”

“…The results demonstrate that the lattice responds more slowly than charge and spin over various length and time scales. The strong hysteresis in the low temperature physical properties 5,13,29,31,32,51 of (La 0.4 Pr 0.6 ) 1.2 Sr 1.8 Mn 2 O 7 derives from these differences. …”

Elastic and magnetic properties of the bilayer manganese oxide(Pr0.6La0.4)1.2Sr1.8Nakanishi1, Shimomura2, Kumagai3 et al. 2007Phys. Rev. B51100View full textAdd to dashboardCite

“…However, a magnetic field could induce a field-induced first-order paramagnetic insulator to ferromagnetic metal transition in this latter compound. In addition, a huge decrease of the c-axis resistivity by a factor of 1 ϫ 10 6 was observed at T = 5 K in the presence of a magnetic field of 5 T. 5,6 The firstorder transition was also accompanied by a remarkable negative magnetoresistance when the field was oriented along the c axis, indicating the presence of an important interplay between spin, carrier, and orbital degrees of freedom. 7,8 A polarized neutron study of this compound revealed an increase in the population of the d͑3z 2 − r 2 ͒ orbitals of Mn 3+ in the field-induced ferromagnetic state when the field was along the c axis.…”

Influence of the rare earth cation (Ln=La, Nd, Sm) on the properties of the Ln0.44Ho0.11Sr0.45MnO3±δ manganite oxides

“…On the other hand, the decrease of the average angle of the Mn-O-Mn bond in the 1 1 0 direction is correlated with a decrease of the molecular magnetization (Tables 2 and 3). By substituting the smaller Nd or Sm cations for La, it can be supposed that the MnO 6 octahedra are elongated on the c axis, favouring the d 3z 2 −r 2 orbital of Mn 3+ [19]. This leads to a decrease of the FM interaction that can result in destruction of the FM state [19].…”