Metal-insulator transition and electroresistance in lanthanum/calcium manganites La1-xCa x MnO3 (x= 0–0.5) from voltage-current-temperature surfaces

Abstract

Of the perovskites, ABX 3 , a subset of special interest is the family in which the A site is occupied by a lanthanide ion, the B site by a transition metal and X is oxygen, as such materials often exhibit a large change in electrical resistance in a magnetic field, a phenomenon known as "colossal" magnetoresistance (MR). Two additional phenomena in this family have also drawn attention: the metal-insulator transition (MIT) and electroresistance (ER). The MIT is revealed by measuring resistance as a function of temperature, and observing a change in the sign of the gradient. ER -the dependence of the resistance on applied current -is revealed by measuring resistance as a function of applied current. Up until now, the phenomena of MIT and ER have been treated separately. Here we report simultaneous observation of the MIT and ER in the lanthanum/calcium manganites. We accomplish this by measuring voltage-current curves over a wide temperature range (10-300 K) allowing us to build up an experimental voltage surface over current-temperature axes. These data directly lead to resistance surfaces. This approach provides additional insight into the phenomena of electrical transport in the lanthanum/calcium manganites, in particular the close connection of the maximum ER to the occurrence of the MIT in those cases of a paramagnetic insulator (PMI) to ferromagnetic metal (FMM) transition.

Magnetic field cycling effect on the non-linear current-voltage characteristics and magnetic field induced negative differential resistance in α-Fe1.64Ga0.36O3 oxide

“…[13][14][15]33 The ferromagnetic loop in our sample does not show any meta-magnetic phase transition, 6 which generally marks for the occurrence of charge ordered structural phase segregation in manganite systems. 21,22 However, the coexistence of magnetically soft and hard phases has been indicated in the M(H) loop in our sample. It is due to random doping of Ga ions in rhombohedral planes containing Fe ions and distribution of magnetic exchange interactions.…”

“…Most striking feature is the magnetic field induced NDR effect. In literature, various models have been discussed to realize the origin of NDR effect, e.g., Joule heating induced phase segregation 21,32 and charge order state, 28,29 space charge limited current (SCLC) mechanism, 14,16,17,22 spin filter and spin valve effect, 25 magnetic domain effect, 19 and charge-spin accumulation and transfer across non-magnetic metal electrode-magnetic semiconductor junctions. [13][14][15]33 The ferromagnetic loop in our sample does not show any meta-magnetic phase transition, 6 which generally marks for the occurrence of charge ordered structural phase segregation in manganite systems.…”

“…The non-linear I-V curves suggest a good amount of change of electrical resistance with bias voltage, a phenomenon known as electroresistance (ER). 22 Fig. 3(a)-3(h) shows the variation of static resistance (R) with bias voltage (V), derived from up and down modes of I-V curves.…”

Small electroresistance (SER) in bulk La2/3Sr1/3MnO3 below

“…Repeated measurements confirmed the data are reproducible and independent of the electrodes used. Further details of the experimental method and examples of the data it yields for lanthanum-calcium manganites are provided by Knott et al [7].…”

Metastability in the resistance of polycrystalline La0.8Li0.2MnO3

“…The perovskite (general form ABO 3 ) La 0.8 Li 0.2 MnO 3 is more specifically a lanthanum manganite (A = La, B = Mn) in which nominally one in five A sites is occupied by Li rather than La. Related compounds have the A site partly occupied by another monovalent species 4, an alkali metal 5, or an alkaline earth 6, 7. Such materials exhibit colossal magnetoresistance (CMR) 8 and colossal electroresistance (CER) 9.…”