Negative magnetization induced by particle-size reduction in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Gd</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>?</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Ca</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>MnO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math> nanoparticle systems

We report a pervasive phenomenon of gradual emergence negative magnetization in typical $R_{1-x}D_x$MnO$_3$ orthorhombic perovskite manganites nano form (with $R^{3+}$ being trivalent high-magnetic-moment ion from the heavier rare-earth elements Gd, Tb, Dy and $D^{2+}$ refers to divalent alkaline Sr, Ca, etc.), while bulk manifests no magnetization. Extensive studies have been carried out Gd$_{1-x}$Ca$_x$MnO$_3$ around half doping. demonstrate experimentally that particle size reduction nano-form enhances propensity system exhibit provide theoretical explanation for phenomenon. To test universality our findings, we extended measurement Dy$_{0.6}$Ca$_{0.4}$MnO$_3$ obtained similar results.