Difference between revisions of "Lanthanum manganite"
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'''Lanthanum manganite''', LaMnO<sub>3</sub>, is a [[mixed oxide]] of [[lanthanum]] and [[manganese]](III). It adopts the [[perovskite structure]]. | '''Lanthanum manganite''', LaMnO<sub>3</sub>, is a [[mixed oxide]] of [[lanthanum]] and [[manganese]](III). It adopts the [[perovskite structure]]. | ||
| − | Lanthanum manganite is usually encountered doped with monovalent or (especially) divalent metal ions such as [[strontium]], to give a compound of formula La<sub>1−''x''</sub>M<sub>''x''</sub>MnO<sub>3</sub>, where ''x'' is typically 0.1–0.2. This forces an equivalent proportion of the manganese ions (double the portion if M is monovalent) to be oxidized from manganese(III) to manganese(IV). These doped lanthanum manganites show [[colossal magnetoresistance]] (CMR).<ref>{{citation | first1 = M. | last1 = McCormack | first2 = S. | last2 = Jin | first3 = T. H. | last3 = Tiefel | first4 = R. M. | last4 = Fleming | first5 = Julia M. | last5 = Phillips | first6 = R. | last6 = Ramesh | title = Very large magnetoresistance in perovskite-like La-Ca-Mn-O thin films | journal = Appl. Phys. Lett. | year = 1994 | volume = 64 | pages = 3045–47 | doi = 10.1063/1.111372}}.</ref><ref>{{citation | first1 = M. K. | last1 = Gubkin | first2 = T. M. | last2 = Perekalina | journal = Pis'ma Zh. Eksp. Teor. Fiz. | year = 1994 | volume = 60 | issue = 10 | pages = 727–30}}; {{citation | title = Nature of the giant magnetoresistance in ferromagnetic lanthanum manganates | url = http://www.jetpletters.ac.ru/ps/1357/article_20515.pdf | journal = JETP Lett. | year = 1994 | volume = 60 | issue = 10 | pages = 747–50}}.</ref> | + | Lanthanum manganite is usually encountered doped with monovalent or (especially) divalent metal ions such as [[strontium]], to give a compound of formula La<sub>1−''x''</sub>M<sub>''x''</sub>MnO<sub>3</sub>, where ''x'' is typically 0.1–0.2. This forces an equivalent proportion of the manganese ions (double the portion if M is monovalent) to be oxidized from manganese(III) to manganese(IV). These doped lanthanum manganites show [[colossal magnetoresistance]] (CMR).<ref>{{citation | first1 = M. | last1 = McCormack | first2 = S. | last2 = Jin | first3 = T. H. | last3 = Tiefel | first4 = R. M. | last4 = Fleming | first5 = Julia M. | last5 = Phillips | first6 = R. | last6 = Ramesh | title = Very large magnetoresistance in perovskite-like La-Ca-Mn-O thin films | journal = Appl. Phys. Lett. | year = 1994 | volume = 64 | pages = 3045–47 | doi = 10.1063/1.111372}}.</ref><ref>{{citation | first1 = M. K. | last1 = Gubkin | first2 = T. M. | last2 = Perekalina | journal = Pis'ma Zh. Eksp. Teor. Fiz. | year = 1994 | volume = 60 | issue = 10 | pages = 727–30}}; {{citation | title = Nature of the giant magnetoresistance in ferromagnetic lanthanum manganates | url = http://www.jetpletters.ac.ru/ps/1357/article_20515.pdf | journal = JETP Lett. | year = 1994 | volume = 60 | issue = 10 | pages = 747–50}}.</ref><ref>{{citation | title = Colossal magnetoresistance | first = A. P. | last = Ramirez | journal = J. Phys.: Cond. Matter | volume = 9 | issue = 39 | pages = 8171 | doi = 10.1088/0953-8984/9/39/005}}.</ref> The strontium-doped material is a [[half-metal]] for ''x'' = 0.3.<ref>{{citation | title = Direct evidence for a half-metallic ferromagnet | first1 = J.-H. | last1 = Park | first2 = E. | last2 = Vescovo | first3 = H.-J. | last3 = Kim | first4 = C. | last4 = Kwon | first5 = R. | last5 = Ramesh | first6 = T. | last6 = Venkatesan | journal = Nature | year = 1998 | volume = 392 | pages = 794–96 | doi = 10.1038/33883}}.</ref> |
==References== | ==References== | ||
Revision as of 14:55, 26 June 2010
Lanthanum manganite, LaMnO3, is a mixed oxide of lanthanum and manganese(III). It adopts the perovskite structure.
Lanthanum manganite is usually encountered doped with monovalent or (especially) divalent metal ions such as strontium, to give a compound of formula La1−xMxMnO3, where x is typically 0.1–0.2. This forces an equivalent proportion of the manganese ions (double the portion if M is monovalent) to be oxidized from manganese(III) to manganese(IV). These doped lanthanum manganites show colossal magnetoresistance (CMR).[1][2][3] The strontium-doped material is a half-metal for x = 0.3.[4]
References
- ↑ McCormack, M.; Jin, S.; Tiefel, T. H.; Fleming, R. M.; Phillips, Julia M.; Ramesh, R. Very large magnetoresistance in perovskite-like La-Ca-Mn-O thin films. Appl. Phys. Lett. 1994, 64, 3045–47. DOI: 10.1063/1.111372.
- ↑ Gubkin, M. K.; Perekalina, T. M. Pis'ma Zh. Eksp. Teor. Fiz. 1994, 60 (10), 727–30; Nature of the giant magnetoresistance in ferromagnetic lanthanum manganates. JETP Lett. 1994, 60 (10), 747–50, <http://www.jetpletters.ac.ru/ps/1357/article_20515.pdf>.
- ↑ Ramirez, A. P. Colossal magnetoresistance. J. Phys.: Cond. Matter, 9 (39), 8171. DOI: 10.1088/0953-8984/9/39/005.
- ↑ Park, J.-H.; Vescovo, E.; Kim, H.-J.; Kwon, C.; Ramesh, R.; Venkatesan, T. Direct evidence for a half-metallic ferromagnet. Nature 1998, 392, 794–96. DOI: 10.1038/33883.
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