Small conductance fluctuations in a second-order colossal magnetoresistive transition

Abstract

Epitaxial films of La 0.72 Sr 0.28 MnO 3 ͑LSMO͒ are found to show almost no excess conductivity fluctuations associated with the colossal-magnetoresistive transition, in contrast to the closely related material La 0.67 Ca 0.33 MnO 3 ͑LCMO͒. The result fits with the contrast between the suspected second-order transition in LSMO and the ͑locally͒ first-order transition and mixed phase in LCMO.

Experimental evidence of correlation between 1/fnoise level and metal-to-insulator transition temperature in epitaxial La0.7Sr0.3MnO3thin films

“…For each film thickness the reported α H /n values reported in table 2 are averaged over several 20 and 50 µm wide microbridges of various lengths (50, 100, or 150 µm). α H /n varied from 2.36 × 10 −31 to 3.41 × 10 −30 m 3 , which is among the lowest values reported for epitaxial LSMO films on STO (0 0 1) substrates, thus reaffirming the high quality of all the tested LSMO films [7,10]. We observed that the 1/f noise level in LSMO is slightly lower on STO substrates than on STO/Si substrates.…”

“…This result could help us to find some indications about the origin of 1/f noise in LSMO thin films. A wide range of results on lowfrequency noise in LSMO thin films, which are sometimes contradictory, can be found in the literature indeed [6][7][8][9][10][11][12][13][14]. It can be explained by the wide variety of sample geometries and structural properties.…”

“…For any kind of sensor, noise level has to be considered in addition to the above cited remarkable properties [5]. Despite previous studies on electronic noise in magnetic materials [6] and more specifically manganites [7], no clear conclusions are given about the physical origin of low-frequency noise in LSMO [8][9][10][11][12][13]. It should be noted that noise measurements in the literature have been carried out under a variety of conditions and geometries on samples with different structural properties.…”

Role of disorder in phase coexistence in manganites: Noise in layered films

“…A standard transfer-line cryostat was used in an electromagnet, with standard measurement techniques similar to those used in earlier works on manganite films. 7,17,18 The new ablated film was prepared as a simple four-probe bar, with width 3 m, length roughly 20 m, and thickness of about 50 nm. All measurements of both noise and resistance used separate current and voltage contacts.…”

All-oxide magnetic field sensor

“…Despite their high figure of merit, TMR junctions based on MgO tunnel barrier often have significant noise compared with GMR [2]. Full spin polarized material like manganite La 0.66 Sr 0.33 MnO 3 (LSMO) are attractive candidates to develop such sensors because LSMO possess a very low 1/f noise when grown on single crystals [3], and a high tunnel magnetoresistance response has been observed with values higher than 100% at 77K [4,5]. Using this kind of tunnel junctions opens possibilities to develop full oxide structures working at liquid nitrogen temperature.…”