Hall effect and conductivity in the single crystals of la sr and la ba manganites
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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) ,

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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.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


1. Introduction and La-Ba manganites

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


Resistivity of la 1 x sr x mno 3 single crystals urushibara et al prb 1995
Resistivity of La and La-Ba manganites1-xSrxMnO3 single crystals(Urushibara et al., PRB 1995)


Resistivity of la 1 x sr x mno 3 single crystals anane et al j phys condens matter 1995
Resistivity of La and La-Ba manganites1-xSrxMnO3 single crystals(Anane et al., J. Phys.:Condens. Matter 1995)


Resistivity of La and La-Ba manganites1-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


Magnetoresistance h 0 0 for la sr single crystals h 10 koe
Magnetoresistance and La-Ba manganitesΔ/=[(H)-(0)]/(0) for La-Sr single crystals (H=10 kOe)


Magnetoresistance for la ba single crystals h 10 koe
Magnetoresistance and La-Ba manganitesΔ/ for La-Ba single crystals (H=10 kOe)


E lectronic specific heat co efficient for la 1 x sr x mno 3 t okuda et al prl 1998
E and La-Ba manganiteslectronic specific heat coefficient γfor La1-xSrxMnO3 (T.Okuda et al. PRL 1998)


Resistivity and thermopower data suggest that in La and La-Ba manganites0.85Sr0.15MnO3 (TC=232 K) and La0.85Ba0.15MnO3 (TC =214 K) variable range hopping (VRH) dominates below 100 K.

Mott’s model

Shklovskii-Efros model


Hall resistivity vs magnetic field for la 0 72 ba 0 28 mno 3 t c 310 k hall r o h r s m
Hall resistivity vs magnetic field for La and La-Ba manganites0.72Ba0.28MnO3 (TC=310 K) Hall=RoH+RsM


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


Low temperature t 200k resistivity in the x x c crystals obeys t 2 law
Low temperature (T< 200K) resistivity in the x>x and La-Ba manganitesc crystals obeys T2-law


Hall mobility in the x x c la sr and la ba single crystals
Hall mobility in the x>x and La-Ba manganitesc La-Sr and La-Ba single crystals


Resistivity and Hall mobility in La and La-Ba manganites2/3(Ca,Pb)1/3MnO3 single crystal (TC≈290 K) calculated on the base of data of Chun et al., PRB 1999.


Anomalous hall coefficient in la 1 x sr x mno 3 single crystals bebenin et al prb 2004
Anomalous Hall coefficient in La and La-Ba manganites1-xSrxMnO3 single crystals (Bebenin et al., PRB 2004)


Hall effect in la 2 3 ca pb 1 3 mno 3 chun et al prb 1999
Hall effect in La and La-Ba manganites2/3(Ca,Pb)1/3MnO3(Chun et al., PRB 1999)




Magnetoresistance of la 0 72 ba 0 28 mno 3 t c 310 k as a function of m 2
Magnetoresistance of La kOe)0.72Ba0.28MnO3 (TC=310 K) as a function of m2


Critical behavior of e 1 t in la 0 72 ba 0 28 mno 3
Critical behavior of E kOe)1(T) in La0.72Ba0.28MnO3


Local activation energy a d ln d t 1 for la 0 85 ba 0 15 mno 3 single crystals
Local activation energy kOe)εa=d(ln)/d(T-1) for La0.85Ba0.15MnO3 single crystals


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


Local activation energy a dln d t 1 in la 1 x sr x mno 3
Local activation energy lightly doped manganites derived from optical measurementsεa=dln/d(T-1) in La1-xSrxMnO3


Conclusion
Conclusion lightly doped manganites derived from optical measurements

  • 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.


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