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Colossal magnetoresistance

December 20, 2023

Not to be confused with Giant magnetoresistance.

Colossal magnetoresistance (CMR) is a property of some materials, mostly manganese-based perovskite oxides, that enables them to dramatically change their electrical resistance in the presence of a magnetic field. The magnetoresistance of conventional materials enables changes in resistance of up to 5%, but materials featuring CMR may demonstrate resistance changes by orders of magnitude.[1][2]

This technology may find uses in disk read-and-write heads, allowing for increases in hard disk drive data density. However, so far it has not led to practical applications because it requires low temperatures and bulky equipment.[3][4]

History edit

Initially discovered in mixed-valence perovskite manganites in the 1950s by G. H. Jonker and J. H. van Santen,[5] a first theoretical description in terms of the double-exchange mechanism was given early on. In this model, the spin orientation of adjacent Mn moments is associated with kinetic exchange of eg-electrons. Consequently, alignment of the Mn spins by an external magnetic field causes higher conductivity. Relevant experimental work was done by Volger,[6] Wollan and Koehler,[7] and later on by Jirak et al.[8] and Pollert et al.[9]

However, the double exchange model did not adequately explain the high insulating-like resistivity above the transition temperature.[10] In the 1990s, work by R. von Helmolt et al.[11] and Jin et al.[12] initiated a large number of further studies. Although there is still no complete understanding of the phenomenon, there is a variety of theoretical and experimental work providing a deeper understanding of the relevant effects.

Theory edit

One prominent model is the so-called half-metallic ferromagnetic model, which is based on spin-polarized (SP) band structure calculations using the local spin-density approximation (LSDA) of the density functional theory (DFT) where separate calculations are carried out for spin-up and spin-down electrons. The half-metallic state is concurrent with the existence of a metallic majority spin band and a nonmetallic minority spin band in the ferromagnetic phase.

This model is not the same as the Stoner Model of itinerant ferromagnetism. In the Stoner model, a high density of states at the Fermi level makes the nonmagnetic state unstable. In SP calculations of covalent ferromagnets using DFT-LSDA functionals, the exchange-correlation integral takes the place of the Stoner parameter. The density of states at the Fermi level does not play a special role.[13] A significant advantage of the half-metallic model is that it does not rely on the presence of mixed valency as does the double exchange mechanism and it can therefore explain the observation of CMR in stoichiometric phases like the pyrochlore Tl
2Mn
2O
7. Microstructural effects in polycrystalline samples have also been investigated and it has been found that the magnetoresistance is often dominated by the tunneling of spin-polarized electrons between grains, resulting in the magnetoresistance having an intrinsic dependence on grain size.[14][15]

A fully quantitative understanding of the CMR effect remains elusive and it is still the subject of much current research. Early promises of the development of new CMR-based technologies have not yet come to fruition.

See also edit

References edit

  1. ^ Ramirez, A. P. (1997). "Colossal magnetoresistance". Journal of Physics: Condensed Matter. 9 (39): 8171–8199. Bibcode:1997JPCM....9.8171R. doi:10.1088/0953-8984/9/39/005. S2CID 19951846.
  2. ^ Rodriguez-Martinez, L.; Attfield, J.P. (1996). "Cation disorder and size effects in magnetoresistive manganese oxide perovskites". Physical Review B. 54 (22): R15622–R15625. Bibcode:1996PhRvB..5415622R. doi:10.1103/PhysRevB.54.R15622. PMID 9985717.
  3. ^ "Chemists exploring new material with 'next generation' computer hard drive possibilities". The University of Aberdeen News. 27 January 2014.
  4. ^ Dagotto, Elbio (14 March 2013). "Brief Introduction to Giant Magnetoresistance (GMR)". Nanoscale Phase Separation and Colossal Magnetoresistance: The Physics of Manganites and Related Compounds. Springer Series in Solid-State Sciences. Vol. 136. Springer Science & Business Media. pp. 395–396. doi:10.1007/978-3-662-05244-0_21. ISBN 9783662052440.
  5. ^ Jonker, G. H.; Van Santen, J. H. (1950). "Ferromagnetic compounds of manganese with perovskite structure". Physica. 16 (3): 337. Bibcode:1950Phy....16..337J. doi:10.1016/0031-8914(50)90033-4.
  6. ^ Volger, J. (1954). "Further experimental investigations on some ferromagnetic oxidic compounds of manganese with perovskite structure". Physica. 20 (1): 49–66. Bibcode:1954Phy....20...49V. doi:10.1016/S0031-8914(54)80015-2.
  7. ^ Wollan, E. O.; Koehler, W. C. (1955). "Neutron Diffraction Study of the Magnetic Properties of the Series of Perovskite-Type Compounds [(1-x)La, x Ca]MnO_{3}". Physical Review. 100 (2): 545. Bibcode:1955PhRv..100..545W. doi:10.1103/PhysRev.100.545.
  8. ^ Jirák, Z.; Krupička, S.; Šimša, Z.; Dlouhá, M.; Vratislav, S. (1985). "Neutron diffraction study of Pr1 − xCaxMnO3 perovskites". Journal of Magnetism and Magnetic Materials. 53 (1–2): 153. Bibcode:1985JMMM...53..153J. doi:10.1016/0304-8853(85)90144-1.
  9. ^ Pollert, E.; Krupička, S.; Kuzmičová, E. (1982). "Structural study of Pr1−xCaxMnO3 and Y1−xCaxMnO3 perovskites". Journal of Physics and Chemistry of Solids. 43 (12): 1137. Bibcode:1982JPCS...43.1137P. doi:10.1016/0022-3697(82)90142-1.
  10. ^ Lalena, J.N.; Cleary, D.A. (2010). Principles of Inorganic Materials Design (2nd ed.). Wiley. p. 361. ISBN 9780470567531.
  11. ^ von Helmolt, R.; Wecker, J.; Holzapfel, B.; Schultz, L.; Samwer, K. (1993). "Giant negative magnetoresistance in perovskitelike La2/3Ba1/3Mn Ox ferromagnetic films". Physical Review Letters. 71 (14): 2331–2333. Bibcode:1993PhRvL..71.2331V. doi:10.1103/PhysRevLett.71.2331. PMID 10054646.
  12. ^ Jin, S.; Tiefel, T. H.; McCormack, M.; Fastnacht, R. A.; Ramesh, R.; Chen, L. H. (1994). "Thousandfold Change in Resistivity in Magnetoresistive La-Ca-Mn-O Films". Science. 264 (5157): 413–5. Bibcode:1994Sci...264..413J. doi:10.1126/science.264.5157.413. PMID 17836905. S2CID 39802144.
  13. ^ Zeller, R. (419–445). Grotendorst, J.; Blũgel, S.; Marx, D. (eds.). Computational Nanoscience: Do It Yourself. NIC Series. Vol. 31. Jũlich: John von Neumann Institute for Computing. p. 2006. ISBN 3-00-017350-1.
  14. ^ Lalena & Cleary 2010, pp. 361–2
  15. ^ For a review see:Dagotto, E. (2003). Nanoscale Phase Separation and Colossal Magnetoresistance. Springer Series in Solid-State Sciences. Springer. ISBN 978-3-662-05244-0.

External links edit

  • "New Clues to Mechanism for Colossal Magnetoresistance". phys.org. 2007.
  • "Materials Science and Technology Division". Physical Sciences Directorate,Oak Ridge National Laboratory.
  • Fontcuberta, Josep (1999). "Colossal magnetoresistance". Phys. World. 12 (2): 33. doi:10.1088/2058-7058/12/2/29.
    • . Physicsweb. February 1999. Archived from the original on 2004-12-13.

December 20, 2023
colossal, magnetoresistance, confused, with, giant, magnetoresistance, property, some, materials, mostly, manganese, based, perovskite, oxides, that, enables, them, dramatically, change, their, electrical, resistance, presence, magnetic, field, magnetoresistan. Not to be confused with Giant magnetoresistance Colossal magnetoresistance CMR is a property of some materials mostly manganese based perovskite oxides that enables them to dramatically change their electrical resistance in the presence of a magnetic field The magnetoresistance of conventional materials enables changes in resistance of up to 5 but materials featuring CMR may demonstrate resistance changes by orders of magnitude 1 2 This technology may find uses in disk read and write heads allowing for increases in hard disk drive data density However so far it has not led to practical applications because it requires low temperatures and bulky equipment 3 4 Contents 1 History 2 Theory 3 See also 4 References 5 External linksHistory editInitially discovered in mixed valence perovskite manganites in the 1950s by G H Jonker and J H van Santen 5 a first theoretical description in terms of the double exchange mechanism was given early on In this model the spin orientation of adjacent Mn moments is associated with kinetic exchange of eg electrons Consequently alignment of the Mn spins by an external magnetic field causes higher conductivity Relevant experimental work was done by Volger 6 Wollan and Koehler 7 and later on by Jirak et al 8 and Pollert et al 9 However the double exchange model did not adequately explain the high insulating like resistivity above the transition temperature 10 In the 1990s work by R von Helmolt et al 11 and Jin et al 12 initiated a large number of further studies Although there is still no complete understanding of the phenomenon there is a variety of theoretical and experimental work providing a deeper understanding of the relevant effects Theory editOne prominent model is the so called half metallic ferromagnetic model which is based on spin polarized SP band structure calculations using the local spin density approximation LSDA of the density functional theory DFT where separate calculations are carried out for spin up and spin down electrons The half metallic state is concurrent with the existence of a metallic majority spin band and a nonmetallic minority spin band in the ferromagnetic phase This model is not the same as the Stoner Model of itinerant ferromagnetism In the Stoner model a high density of states at the Fermi level makes the nonmagnetic state unstable In SP calculations of covalent ferromagnets using DFT LSDA functionals the exchange correlation integral takes the place of the Stoner parameter The density of states at the Fermi level does not play a special role 13 A significant advantage of the half metallic model is that it does not rely on the presence of mixed valency as does the double exchange mechanism and it can therefore explain the observation of CMR in stoichiometric phases like the pyrochlore Tl2 Mn2 O7 Microstructural effects in polycrystalline samples have also been investigated and it has been found that the magnetoresistance is often dominated by the tunneling of spin polarized electrons between grains resulting in the magnetoresistance having an intrinsic dependence on grain size 14 15 A fully quantitative understanding of the CMR effect remains elusive and it is still the subject of much current research Early promises of the development of new CMR based technologies have not yet come to fruition See also editGiant magnetoresistanceReferences edit Ramirez A P 1997 Colossal magnetoresistance Journal of Physics Condensed Matter 9 39 8171 8199 Bibcode 1997JPCM 9 8171R doi 10 1088 0953 8984 9 39 005 S2CID 19951846 Rodriguez Martinez L Attfield J P 1996 Cation disorder and size effects in magnetoresistive manganese oxide perovskites Physical Review B 54 22 R15622 R15625 Bibcode 1996PhRvB 5415622R doi 10 1103 PhysRevB 54 R15622 PMID 9985717 Chemists exploring new material with next generation computer hard drive possibilities The University of Aberdeen News 27 January 2014 Dagotto Elbio 14 March 2013 Brief Introduction to Giant Magnetoresistance GMR Nanoscale Phase Separation and Colossal Magnetoresistance The Physics of Manganites and Related Compounds Springer Series in Solid State Sciences Vol 136 Springer Science amp Business Media pp 395 396 doi 10 1007 978 3 662 05244 0 21 ISBN 9783662052440 Jonker G H Van Santen J H 1950 Ferromagnetic compounds of manganese with perovskite structure Physica 16 3 337 Bibcode 1950Phy 16 337J doi 10 1016 0031 8914 50 90033 4 Volger J 1954 Further experimental investigations on some ferromagnetic oxidic compounds of manganese with perovskite structure Physica 20 1 49 66 Bibcode 1954Phy 20 49V doi 10 1016 S0031 8914 54 80015 2 Wollan E O Koehler W C 1955 Neutron Diffraction Study of the Magnetic Properties of the Series of Perovskite Type Compounds 1 x La x Ca MnO 3 Physical Review 100 2 545 Bibcode 1955PhRv 100 545W doi 10 1103 PhysRev 100 545 Jirak Z Krupicka S Simsa Z Dlouha M Vratislav S 1985 Neutron diffraction study of Pr1 xCaxMnO3 perovskites Journal of Magnetism and Magnetic Materials 53 1 2 153 Bibcode 1985JMMM 53 153J doi 10 1016 0304 8853 85 90144 1 Pollert E Krupicka S Kuzmicova E 1982 Structural study of Pr1 xCaxMnO3 and Y1 xCaxMnO3 perovskites Journal of Physics and Chemistry of Solids 43 12 1137 Bibcode 1982JPCS 43 1137P doi 10 1016 0022 3697 82 90142 1 Lalena J N Cleary D A 2010 Principles of Inorganic Materials Design 2nd ed Wiley p 361 ISBN 9780470567531 von Helmolt R Wecker J Holzapfel B Schultz L Samwer K 1993 Giant negative magnetoresistance in perovskitelike La2 3Ba1 3Mn Ox ferromagnetic films Physical Review Letters 71 14 2331 2333 Bibcode 1993PhRvL 71 2331V doi 10 1103 PhysRevLett 71 2331 PMID 10054646 Jin S Tiefel T H McCormack M Fastnacht R A Ramesh R Chen L H 1994 Thousandfold Change in Resistivity in Magnetoresistive La Ca Mn O Films Science 264 5157 413 5 Bibcode 1994Sci 264 413J doi 10 1126 science 264 5157 413 PMID 17836905 S2CID 39802144 Zeller R 419 445 Grotendorst J Blũgel S Marx D eds Computational Nanoscience Do It Yourself NIC Series Vol 31 Jũlich John von Neumann Institute for Computing p 2006 ISBN 3 00 017350 1 Lalena amp Cleary 2010 pp 361 2 For a review see Dagotto E 2003 Nanoscale Phase Separation and Colossal Magnetoresistance Springer Series in Solid State Sciences Springer ISBN 978 3 662 05244 0 External links edit New Clues to Mechanism for Colossal Magnetoresistance phys org 2007 Materials Science and Technology Division Physical Sciences Directorate Oak Ridge National Laboratory Fontcuberta Josep 1999 Colossal magnetoresistance Phys World 12 2 33 doi 10 1088 2058 7058 12 2 29 Colossal magnetoresistance Physicsweb February 1999 Archived from the original on 2004 12 13 Retrieved from https en wikipedia org w index php title Colossal magnetoresistance amp oldid 1127449577, wikipedia, wiki, book, books, library,

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