Giant volume magnetostriction in manganites and its connection with colossal magnetoresistance
|Liudmila I. Koroleva , Roman V. Demin , Alexey V. Michurin , Anna I. Abramovich|
M.V. Lomonosov Moscow State University, Vorobyevy gory, Moscow 119992, Russian Federation
Giant volume magnetostriction ~ 10-4 - 10-3 near Curie point TC is found in A1-xSrxMnO3 (A = Sm, Nd and La). This discovery make possible the magneto-mechanical devices on a basis of manganites. In this work the elastic, magneto-elastic, magnetic and electrical properties of La1-xSrxMnO3 (x = 0.1, 0.125, 0.15, 0.3) single crystals, and A1-xSrxMnO3 (A = Nd, Sm; x = 0.33, 0.4, 0.45) ceramics are studied. For all the samples a volume magnetostriction w is nega-tive and the |w|(T) curves go through maximum near of TC. At T ł TC thermal expansion Dl/l exceeds linear on T thermal expansion. The behavior of CMR and w near TC are similar in Lai-xSrxMnO3: isotherms are not saturated up to the maximum field of measurement ~ 120 kOe; both of them are negative; the maximum magnitudes, taken place near TC, decrease with the rise of x. Similar behavior of CMR and w was observed for A1-xSrxMnO3 (A = Nd, Sm, x = 0.33). However the behavior of w and CMR was different in compounds with x = 0.4 and 0.45 of Sm1-xSrxMnO3 system, in which ferromagnetic (F), anti-ferromagnetic (AF) of A-type and of CE-type charge ordering (CO) clusters were observed from neutron diffraction. Both F and A-type AF clusters break down in the TC - region and CO AF clusters remain at T > TC. Here the transi-tion of CO clusters to F state, induced by magnetic field H, is accompanied by the sharp jumps on isotherms of magnetization, magnetoresistance and volume magnetistriction at H ~ HC1 and their saturation is achieved at H ~ HC2. This transition leads to CMR and giant magnetostriction (~ 10-3); to say, CMR and giant magnetostriction take place in that case when F ordering regions increase by the magnetic field at T ł TC. Peculiarities of w, Dl/l and CMR near TC are explained magnetic two-phase F-AF state due to strong s-d exchange .
Presentation: oral at E-MRS Fall Meeting 2003, Symposium D, by Liudmila I. Koroleva
See On-line Journal of E-MRS Fall Meeting 2003
Submitted: 2003-05-06 12:33 Revised: 2009-06-08 12:55