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

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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


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

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


Resistivity of la 1 x sr x mno 3 single crystals urushibara et al prb 1995

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


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

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


Magnetoresistance h 0 0 for la sr single crystals h 10 koe

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


Magnetoresistance for la ba single crystals h 10 koe

Magnetoresistance Δ/ 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

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


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

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


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 La0.72Ba0.28MnO3 (TC=310 K) Hall=RoH+RsM


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

Hall mobility in the single crystals with x<xc.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>xc crystals obeys T2-law


Hall mobility in the x x c la sr and la ba single crystals

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


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

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.


Anomalous hall coefficient in la 1 x sr x mno 3 single crystals bebenin et al prb 2004

Anomalous Hall coefficient in La1-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 La2/3(Ca,Pb)1/3MnO3(Chun et al., PRB 1999)


Resistivity of la sr single crystals near curie temperature

Resistivity of La-Sr single crystals near Curie temperature


Resistivity of la ba crystals near curie temperature h 10 koe o exp e o e 1 m 2 k b t

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


Magnetoresistance of la 0 72 ba 0 28 mno 3 t c 310 k as a function of m 2

Magnetoresistance of La0.72Ba0.28MnO3 (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 E1(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 εa=d(ln)/d(T-1) for La0.85Ba0.15MnO3 single crystals


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

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 εa=dln/d(T-1) in La1-xSrxMnO3


Conclusion

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.


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