Far-infrared absorption of La1-xCaxMnO3-y at high pressure.
The first far-infrared absorption spectra of manganite samples at pressures P up to 10 GPa were obtained on La1-xCaxMnO3-y by use of synchrotron radiation. For x=0.25 and 0.20 (y=0), P promotes partial metallization at room temperature through a strong reduction of the insulating gap. An x=0.20 sample with y=0.08 does not show any charge delocalization effect up to 10 GPa. An Urbach-like model of disordered Jahn-Teller wells is shown to well fit the far-infrared band edge and allows one to obtain a reliable pressure dependence of the energy gap.
Coherentia CNR-INFM and Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 2, I-00185 Roma, Italy.
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Sacchetti
M Cestelli
MC
Guidi
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E
Arcangeletti
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A
Nucara
P
P
Calvani
M
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Piccinini
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Marcelli
P
P
Postorino