We present ultrasonic measurements on magnetoresistance manganites
Pr1-xCaxMnO3 (x= 0.35,0.5) in magnetic fields up to 27T. Charge
ordering occurs in Pr1-xCaxMnO3 in the 0.35<x<0.5 composition regime.
The associated lattice distortions also exhibit long-range ordering. A
large decrease (1%) of the sound velocity was observed at the
insulator-to-metal transition induced by magnetic field destroying the
charge ordering. The insulator-metal transition for Pr0.5Ca0.5MnO3 is
accompanied with a large hysteresis which extends up to 20 T at the
lowest temperatures (2 K). The field dependence of the longitudinal
sound velocity measured on polycrystalline samples are reported and the
magnetic diagram is determined. (C) 2003 Elsevier B.V. All rights
reserved.</textarea>
</td>
<TD ALIGN="left" WIDTH="10%">
<A HREF="javascript:window.open('http://edoc.mpg.de/addon.epl?mode=methelp&whgen=3&whele=abstract','','scrollbars');void('')" ><img src="images/hilfe.gif" border="0" /></a>
</td></tr>
<tr><TD ALIGN="right" WIDTH="30%">
Abstract (Markup) </td>
<TD ALIGN="left" WIDTH="60%">
<textarea name="markupabstract" ROWS="5" COLS="60">
