Hydrostatic pressure effect on electrical and magnetic properties of electron-doped R_0.16Ca_0.84MnO₃ (R=Pr, Gd, Eu)

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• 作者：I. Medvedeva ; A. Maignan ; C. Martin ; K. Bä ; rner ; B. Raveau ; Yu. Bersenev ; N. Mushnikov and E. Gerasimov
• 关键词：Electron-doped manganites ; Hydrostatic pressure ; Magnetic and electronic transition temperature
• 刊名：Physica B
• 出版年：2005
• 出版时间：2005
• 年：2005
• 卷：365
• 期：1-4
• 页码：114-120
• 全文大小：373 K

文摘

Temperature dependences of resistivity and magnetization of electron-doped R_0.16Ca_0.84MnO₃ (R=Pr, Gd, Eu) orthomanganites have been studied under applied pressures up to 11 kbar. For Pr_0.16Ca_0.84MnO₃, the transition temperature between antiferromagnetic insulating and paramagnetic semi-metallic state tyle=""text-decoration:none; color:black"" href=""/science?_ob=MathURL&_method=retrieve&_udi=B6TVH-4GD4SKC-1&_mathId=mml1&_user=10&_cdi=5535&_rdoc=16&_handle=V-WA-A-W-BB-MsSWYVW-UUW-U-AABZWDCZDC-AABBYCZVDC-CADVWEDAA-BB-U&_acct=C000050221&_version=1&_userid=10&md5=2e9fb70097b47153152aefcc767bb54f"" title=""Click to view the MathML source"">T_t decreases under pressure at the rate cience?_ob=MathURL&_method=retrieve&_udi=B6TVH-4GD4SKC-1&_mathId=mml2&_user=10&_cdi=5535&_rdoc=16&_handle=V-WA-A-W-BB-MsSWYVW-UUW-U-AABZWDCZDC-AABBYCZVDC-CADVWEDAA-BB-U&_acct=C000050221&_version=1&_userid=10&md5=70e48138ae8e0eaa62be9a44f23ff485"">c=""http://www.sciencedirect.com/cache/MiamiImageURL/B6TVH-4GD4SKC-1-S/0?wchp=dGLbVtz-zSkzS"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=17 width=165>. The sign of the effect is opposite and the value is an order of magnitude lower than that for ferromagnetic metallic hole-doped R_1−xD_xMnO₃ (tyle=""text-decoration:none; color:black"" href=""/science?_ob=MathURL&_method=retrieve&_udi=B6TVH-4GD4SKC-1&_mathId=mml3&_user=10&_cdi=5535&_rdoc=16&_handle=V-WA-A-W-BB-MsSWYVW-UUW-U-AABZWDCZDC-AABBYCZVDC-CADVWEDAA-BB-U&_acct=C000050221&_version=1&_userid=10&md5=e36d93a09dad6e9dfce3d38118661228"" title=""Click to view the MathML source"">x_C<x<0.5, D=Ca, Sr, tyle=""text-decoration:none; color:black"" href=""/science?_ob=MathURL&_method=retrieve&_udi=B6TVH-4GD4SKC-1&_mathId=mml4&_user=10&_cdi=5535&_rdoc=16&_handle=V-WA-A-W-BB-MsSWYVW-UUW-U-AABZWDCZDC-AABBYCZVDC-CADVWEDAA-BB-U&_acct=C000050221&_version=1&_userid=10&md5=5b5cf9210d11b17e962e3451722d6c8b"" title=""Click to view the MathML source"">x_C—percolation threshold) compounds. The negative sign of the effect is in evident contradiction with a positive shift of the magnetic transition temperature of the parent compound CaMnO₃. To interpret this result, a possibility of electron delocalization and a crossover to a band antiferromagnetism by electron doping have been suggested.

The compounds Eu_0.16Ca_0.84MnO₃ and Gd_0.16Ca_0.84MnO₃ below tyle=""text-decoration:none; color:black"" href=""/science?_ob=MathURL&_method=retrieve&_udi=B6TVH-4GD4SKC-1&_mathId=mml5&_user=10&_cdi=5535&_rdoc=16&_handle=V-WA-A-W-BB-MsSWYVW-UUW-U-AABZWDCZDC-AABBYCZVDC-CADVWEDAA-BB-U&_acct=C000050221&_version=1&_userid=10&md5=7e41ca80db3a899319170874702f125f"" title=""Click to view the MathML source"">T_t are in a mixed magnetic state with coexisting ferro- and antiferromagnetic exchange interactions. The weak pressure effect on tyle=""text-decoration:none; color:black"" href=""/science?_ob=MathURL&_method=retrieve&_udi=B6TVH-4GD4SKC-1&_mathId=mml6&_user=10&_cdi=5535&_rdoc=16&_handle=V-WA-A-W-BB-MsSWYVW-UUW-U-AABZWDCZDC-AABBYCZVDC-CADVWEDAA-BB-U&_acct=C000050221&_version=1&_userid=10&md5=1c57a4565249a8b72f8a8085cca17811"" title=""Click to view the MathML source"">T_t for Eu_0.16Ca_0.84MnO₃ does not correlate with the record of the magnetoresistance effect of electron-doped compounds. Considering the obtained applied pressure data, the role of interatomic distances in the formation of CMR effect for electron-doped orthomanganites is discussed.