1 / 24

Hall effect and conductivity in the single crystals of La-Sr and La-Ba manganites

Hall effect and conductivity in the single crystals of La-Sr and La-Ba manganites. N . G . Bebenin 1) , R . I . Zainullina 1) , N . S . Chusheva 1) , V . V . Ustinov 1) , Ya . M . Mukovskii 2) ,

jela
Download Presentation

Hall effect and conductivity in the single crystals of La-Sr and La-Ba manganites

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Hall effect and conductivity in the single crystals of La-Sr and La-Ba manganites N.G.Bebenin1),R.I.Zainullina1), N.S.Chusheva1), V.V.Ustinov1), Ya.M.Mukovskii2), 1)Institute of Metal Physics, UD RAS, Ekaterinburg, Russia2)Moscow State Steel & Alloys Institute, Moscow, Russia

  2. 1. Introduction 2. Resistivity and Hall effect far below Curie temperature 2.1. The x<xc crystals: La0.85Sr0.15MnO3, La0.85Ba0.15MnO3, and La0.80Ba0.20MnO3 2.2. The x>xc crystals: La0.80Sr0.20MnO3, La0.75Sr0.25MnO3, and La0.72Ba0.28MnO3 3. Temperature-induced metal-semiconductor transition 4. Near TC and in the paramagnetic state 5. Conclusion

  3. Resistivity of La1-xSrxMnO3 single crystals(Urushibara et al., PRB 1995)

  4. Resistivity of La1-xSrxMnO3 single crystals(Anane et al., J. Phys.:Condens. Matter 1995)

  5. Resistivity of La1-xSrxMnO3 and La1-xBaxMnO3 single crystals(Bebenin et al., PRB 2004, JETP 2000, J. Phys.: Condens. Matter 2005, JMMM 2006)Blue line: inverse minimum metallic conductivity, σmin-1, according to Salamon and Jaime, RMP 2001

  6. Magnetoresistance Δ/=[(H)-(0)]/(0) for La-Sr single crystals (H=10 kOe)

  7. Magnetoresistance Δ/ for La-Ba single crystals (H=10 kOe)

  8. Electronic specific heat coefficient γfor La1-xSrxMnO3 (T.Okuda et al. PRL 1998)

  9. Resistivity and thermopower data suggest that in La0.85Sr0.15MnO3 (TC=232 K) and La0.85Ba0.15MnO3 (TC =214 K) variable range hopping (VRH) dominates below 100 K. Mott’s model Shklovskii-Efros model

  10. Hall resistivity vs magnetic field for La0.72Ba0.28MnO3 (TC=310 K) Hall=RoH+RsM

  11. Hall mobility in the single crystals with x<xc.xc=0.17 for La1-xSrxMnO3, xc≈0.22 for La1-xBaxMnO3

  12. Low temperature (T< 200K) resistivity in the x>xc crystals obeys T2-law

  13. Hall mobility in the x>xc La-Sr and La-Ba single crystals

  14. Resistivity and Hall mobility in La2/3(Ca,Pb)1/3MnO3 single crystal (TC≈290 K) calculated on the base of data of Chun et al., PRB 1999.

  15. Anomalous Hall coefficient in La1-xSrxMnO3 single crystals (Bebenin et al., PRB 2004)

  16. Hall effect in La2/3(Ca,Pb)1/3MnO3(Chun et al., PRB 1999)

  17. Resistivity of La-Sr single crystals near Curie temperature

  18. Resistivity of La-Ba crystals near Curie temperature (H=10 kOe)=oexp[(Eo-E1m2)/kBT)

  19. Magnetoresistance of La0.72Ba0.28MnO3 (TC=310 K) as a function of m2

  20. Critical behavior of E1(T) in La0.72Ba0.28MnO3

  21. Local activation energy εa=d(ln)/d(T-1) for La0.85Ba0.15MnO3 single crystals

  22. Temperature dependence of the metallic phase volume in some lightly doped manganites derived from optical measurements (Mostovshchikova et al., PRB 2004)

  23. Local activation energy εa=dln/d(T-1) in La1-xSrxMnO3

  24. Conclusion • Unlike La1-xSrxMnO3 family, in the x>xc La1-xBaxMnO3 single crystals electrons – not holes - are majority carriers. Thus the band structure depends on not only doping level but also on type of divalent ion. • The temperature-induced metal-semiconductor transition, if any, occurs well below TC. • Near Curie temperature, where CMR effect is observed, all the crystals are in a semiconductor state. Above TC, the crystals are likely to be in the semiconductor state, too. The sign of d/dT is not a sufficient indication of metallic state. • The conductivity mechanisms in the manganites with different doping is different. A general formal reason for the CMR effect in the La-Sr and La-Ba single crystals consists in the change of activation energy under application of a magnetic field.

More Related