Correlation between the magnetic and thermoelectric properties in Mg_{2&#x2212;<i>x</i>}Mn_<i>x</i>Si

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>Single crystals of Mg<SUB>2−<I>x</I> </SUB>Mn<SUB> <I>x</I> </SUB>Si (<I>x</I> = 0, 0.1, 0.2, 0.3, and 0.4) were prepared using a vertical Bridgman method. The formation of desired materials was confirmed using single-crystal and powder X-ray diffraction. The thermoelectric and magnetic properties were investigated for various Mn contents in the temperature range between 2 and 300 K and in magnetic fields up to 70 kOe. For various <I>x</I> values, Mg<SUB>2−<I>x</I> </SUB>Mn<SUB> <I>x</I> </SUB>Si with <I>x</I> = 0.2 possesses the highest figure of merit. The experimental results revealed that the substitutional Mn atoms exhibit mixed valences of +3 (majority) and +2, giving rise to dramatic changes of carrier density and magnetic interaction. At the same time, the Seebeck coefficient and magnetic susceptibility show a sudden change at the same temperature. These results imply that the thermoelectric properties are correlated with the magnetic properties in the Mg<SUB>2−<I>x</I> </SUB>Mn<SUB> <I>x</I> </SUB>Si crystals.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Single crystals of Mg<SUB>2−x</SUB>Mn<SUB>x</SUB>Si were prepared by using a vertical Bridgman method. </LI> <LI> The thermoelectric performance was improved as doping Mn into Mg<SUB>2</SUB>Si. </LI> <LI> The magnetic properties were enhanced with Mn dopants. </LI> <LI> The thermoelectric and magnetic properties were strongly correlated in Mg<SUB>2−x</SUB>Mn<SUB>x</SUB>Si. </LI> </UL> </P>