Geshev, Julian Penkov

Applied Physics Letters

English

Lume 5.8

Comment on “Cluster glass induced exchange biaslike effect in the perovskitecobaltites” [Appl. Phys. Lett.90, 162515 (2007)]J. Geshev  Citation: Applied Physics Letters 93, 176101 (2008); doi: 10.1063/1.3009550 View online: http://dx.doi.org/10.1063/1.3009550 View Table of Contents: http://scitation.aip.org/content/aip/journal/apl/93/17?ver=pdfcov Published by the AIP Publishing  Articles you may be interested in Comment on “Zero-field cooled exchange bias in hexagonal YMnO3 nanoparticles” [Appl. Phys. Lett. 103,042416 (2013)] Appl. Phys. Lett. 104, 156101 (2014); 10.1063/1.4871708  Comment on “Exchange bias in the layered cobaltite Sr 1.5 Pr 0.5 CoO 4 ” [J. Appl. Phys.104, 023914 (2008)] J. Appl. Phys. 105, 066108 (2009); 10.1063/1.3098262  Response to “Comment on ‘Cluster glass induced exchange biaslike effect in the perovskite cobaltites’ ” [Appl.Phys. Lett. 93, 176101 (2008)] Appl. Phys. Lett. 93, 176102 (2008); 10.1063/1.3009551  Cluster glass induced exchange biaslike effect in the perovskite cobaltites Appl. Phys. Lett. 90, 162515 (2007); 10.1063/1.2730737  Comment on “Exchange bias-like phenomenon in Sr Ru O 3 ” [Appl. Phys. Lett.88, 102502 (2006)] Appl. Phys. Lett. 89, 036101 (2006); 10.1063/1.2222246    Reuse of AIP Publishing content is subject to the terms at: https://publishing.aip.org/authors/rights-and-permissions. Download to IP:  143.54.44.137 On: Wed, 04 May2016 19:35:59Comment on “Cluster glass induced exchange biaslike effect in theperovskite cobaltites” †Appl. Phys. Lett. 90, 162515 „2007…‡J. GeshevaInstituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, 91501-970 RioGrande do Sul, BrazilReceived 25 August 2008; accepted 8 October 2008; published online 29 October 2008DOI: 10.1063/1.3009550Recently, Luo and Wang1 reported that magnetizationhysteresis loops of bulk Ba-doped LaCoO3 shifted bothalong the field and the magnetization axes. As previouslycommented2,3 the shift away from the zero-field axis, whichis the most known manifestation of the exchange biaseffect,4–6 is estimated from a loop of a magnetically saturatedsystem. In the letter of Luo and Wang,1 however, one readsthat magnetic fields as high as 100 kOe are still not sufficientto saturate the samples at low temperatures see also theirFig. 4 and it is clearly seen in Fig. 2 that the loop tracedusing the maximum measurement field of 3 kOe is notclosed. Ignoring these facts, the authors attributed the shiftsto exchange bias effect due to freezing properties of localanisotropy in a cluster glass system.Actually, since both shifts have been extracted from mi-nor nonsaturated hysteresis loops, one cannot affirm thatthe displacement from the origin evidences exchange biasmanifestation. Minor loops traced after saturation are natu-rally displaced along both the field and magnetization axes.Figure 4 in the letter commented here is a typical example ofa sequence of minor hysteresis loops. Detailed discussion onthis subject can be found in Ref. 3.One notes that the letter of Luo and Wang1 refers to awork of Pi et al.7 on SrRuO3 where similar “exchange bias-like” behavior has been reported. In a subsequent erratum,8however, Pi et al.7 admitted that it is incorrect to associatethe observed shifts with exchange bias, the reason being thenonsaturation of their samples. Apparently, this erratum hasremained unnoticed by Luo and Wang.1In summary, the present comment asserts that the workof Luo and Wang1 does not provide sufficient proofs that themeasured displacements along the field and the magnetiza-tion axes are manifestations of the exchange bias effect intheir bulk Ba-doped LaCoO3. All observed characteristics areconsistent with the typical behavior of minor hysteresisloops.This work was supported by CNPq, Brazil.1W. Luo and F. Wang, Appl. Phys. Lett. 90, 162515 2007.2L. Klein, Appl. Phys. Lett. 89, 036101 2006.3J. Geshev, J. Magn. Magn. Mater. 320, 600 2008.4W. H. Meiklejohn and C. P. Bean, Phys. Rev. 102, 1413 1956; 105, 9041957.5J. Nogués and I. K. Schuller, J. Magn. Magn. Mater. 192, 203 1999.6A. E. Berkowitz and K. Takano, J. Magn. Magn. Mater. 200, 552 1999.7L. Pi, S. Zhang, S. Tan, and Y. Zhang, Appl. Phys. Lett. 88, 1025022006.8L. Pi, S. Zhang, S. Tan, and Y. Zhang, Appl. Phys. Lett. 89, 0399022006.aElectronic mail: julian@if.ufrgs.br.APPLIED PHYSICS LETTERS 93, 176101 20080003-6951/2008/9317/176101/1/$23.00 © 2008 American Institute of Physics93, 176101-1 Reuse of AIP Publishing content is subject to the terms at: https://publishing.aip.org/authors/rights-and-permissions. Download to IP:  143.54.44.137 On: Wed, 04 May2016 19:35:59

Comment on “Cluster glass induced exchange biaslike effect in the perovskite cobaltites” [Appl. Phys. Lett. 90, 162515 (2007)]

Universidade Federal do Rio Grande do Sul

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Comment on “Cluster glass induced exchange biaslike effect in the perovskite cobaltites” [Appl. Phys. Lett. 90, 162515 (2007)]

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