COERCIVE FORCE IN THE SYSTEM OF FERROMAGNETIC GRANULES FOR HALF METAL CrO2 WITH PERCOLATION CONDUCTIVITY
Keywords:
half-metal, ferromagnets, tunneling magnetoresistance, granular systems, percolation, magnetization, coercive force
Abstract
Magnetic and magnetoresistive properties of several samples of compacted powders of ferromagnetic half-metal CrO2, consisting of needle-shaped or spherical nanoparticles coated with thin dielectric shells, were investigated in wide temperature range. The temperature dependence of the coercive force Hc(T) is compared with the temperature dependence of the field of maximum of positive tunneling magnetoresistance Hp(T). The dependence of Hp(T) was nonmonotonic one. It is found that in the low-temperature range (4.2 ÷ 70 K) the ratio Hp ≈ Hc, expected for compacted ferromagnetic powders with particles of submicron sizes, does not fulfilled. It is assumed that the possible reason of the difference between Hp and Hc is the mismatch between the orientation of the global magnetization of the entire sample and the orientations of the magnetic moments in some part of granules that form the optimal conducting channels at low temperatures. Such a mismatch may be due to the multidomain granules are more prone to the formation of optimal conducting chains in the transport channels. That leads to a change in the mechanism of magnetization reversal in these channels and to violation of the ratio Hp ≈ Hc.Downloads
Download data is not yet available.
References
1. Lewis S.P., Allen P.B., Sasaki T. Band structure and transport properties of CrO2 // Phys. Rev. B. – 1997. – Vol. 55. – P.10253-10260.
2. Osmolowskaya O.M., Arkhipov D.I., Gordeev S.V., Dzidziguri E.L., Osmolowsky M.G. Synthesis of single-domain chromium dioxide nanoparticles with high coercive force // Zhurnal Obschej Khimii. – 2015. – Vol. 85. – P.1-3.
3. Ziese M. Extrinsic magnetotransport phenomena in ferromagnetic oxides // Rep. Progr. Phys. – 2002. – Vol. 65. – P.143-249.
4. Coey J.M.D. Powder Magneto-resistance // J. Appl. Phys. – 1999. – Vol. 85. – P. 5576-5581.
5. Coey J.M.D., Berkowitz A.E., Balcells Ll., Putris F.F., Barry A. Magnetoresistance of Chromium Dioxide Powder Compacts // Phys. Rev. Lett. – 1998. – Vol.
80. – P.3815-3818.
6. Belevtsev B.I., Dalakova N.V., Osmolowsky M.G., Beliayev E.Yu., Selutin A.A. Transport and magnetotransport properties of cold-pressed CrO2 powder, prepared by hydrothermal synthesis // J. Alloys Comp. – 2009. – Vol. 479. – P.11-16.
7. Dalakova N.V., Belevtsev B.I., Beliayev E.Yu., Bludov O.M., Pashchenko V.N., Osmolowsky M.G., Osmolowskaya O.M. Resistive and magnetoresistive properties of compacted CrO2 powders with different types of intergranular dielectric layers // Low Temperature Physics. – 2012. – Vol. 38. – P. 1422-1432.
8. Osmolovskii M.G., Kozhina I.I., Ivanova L.Yu., Baidakova O.L. Hydrothermal Synthesis of Chromium Dioxide // Russian Journal of Appl. Chem. – 2001. – Vol. 74. – P.1-6.
9. Bondarewsky S.I., Eremin V.V., Panchuk V.V., Semenov V.G., Osmolowsky M.G. Mössbauer study of the state of iron atoms in modified chromium dioxide // Fizika Tverdogo Tela (FTT). – 2016. – Vol. 68. – P.77-81.
10. Panagiotopoulos I., Moutis N., Ziese M., Bollero A. Magnetoconductance and hysteresis in milled La0.67Sr0.33MnO3 powder compacts // J. Magn. Magn. Mater. – 2006. – Vol. 299. – P. 94-104.
11. Kolesnichenko Yu.А., Dalakova N.V., Beliayev Е.Yu, Bludov O.M., Horielyi V.А., Osmolowskaya О.М., Osmolowsky М.G. Features of low-temperature tunneling magnetoresistance of pressed nanopowders of chromium dioxide CrO2 // Low Temperature Physics. – 2017. – Vol. 43. – P.772-781.
2. Osmolowskaya O.M., Arkhipov D.I., Gordeev S.V., Dzidziguri E.L., Osmolowsky M.G. Synthesis of single-domain chromium dioxide nanoparticles with high coercive force // Zhurnal Obschej Khimii. – 2015. – Vol. 85. – P.1-3.
3. Ziese M. Extrinsic magnetotransport phenomena in ferromagnetic oxides // Rep. Progr. Phys. – 2002. – Vol. 65. – P.143-249.
4. Coey J.M.D. Powder Magneto-resistance // J. Appl. Phys. – 1999. – Vol. 85. – P. 5576-5581.
5. Coey J.M.D., Berkowitz A.E., Balcells Ll., Putris F.F., Barry A. Magnetoresistance of Chromium Dioxide Powder Compacts // Phys. Rev. Lett. – 1998. – Vol.
80. – P.3815-3818.
6. Belevtsev B.I., Dalakova N.V., Osmolowsky M.G., Beliayev E.Yu., Selutin A.A. Transport and magnetotransport properties of cold-pressed CrO2 powder, prepared by hydrothermal synthesis // J. Alloys Comp. – 2009. – Vol. 479. – P.11-16.
7. Dalakova N.V., Belevtsev B.I., Beliayev E.Yu., Bludov O.M., Pashchenko V.N., Osmolowsky M.G., Osmolowskaya O.M. Resistive and magnetoresistive properties of compacted CrO2 powders with different types of intergranular dielectric layers // Low Temperature Physics. – 2012. – Vol. 38. – P. 1422-1432.
8. Osmolovskii M.G., Kozhina I.I., Ivanova L.Yu., Baidakova O.L. Hydrothermal Synthesis of Chromium Dioxide // Russian Journal of Appl. Chem. – 2001. – Vol. 74. – P.1-6.
9. Bondarewsky S.I., Eremin V.V., Panchuk V.V., Semenov V.G., Osmolowsky M.G. Mössbauer study of the state of iron atoms in modified chromium dioxide // Fizika Tverdogo Tela (FTT). – 2016. – Vol. 68. – P.77-81.
10. Panagiotopoulos I., Moutis N., Ziese M., Bollero A. Magnetoconductance and hysteresis in milled La0.67Sr0.33MnO3 powder compacts // J. Magn. Magn. Mater. – 2006. – Vol. 299. – P. 94-104.
11. Kolesnichenko Yu.А., Dalakova N.V., Beliayev Е.Yu, Bludov O.M., Horielyi V.А., Osmolowskaya О.М., Osmolowsky М.G. Features of low-temperature tunneling magnetoresistance of pressed nanopowders of chromium dioxide CrO2 // Low Temperature Physics. – 2017. – Vol. 43. – P.772-781.
Published
2017-10-20
Cited
How to Cite
Dalakova, N. V., Beliayev, E. Y., & Horielyi, V. A. (2017). COERCIVE FORCE IN THE SYSTEM OF FERROMAGNETIC GRANULES FOR HALF METAL CrO2 WITH PERCOLATION CONDUCTIVITY. East European Journal of Physics, 4(3), 78-84. https://doi.org/10.26565/2312-4334-2017-3-11
Section
Original Papers
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgment of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgment of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).
