文摘
The effects of Cr3+ ions doping on the magnetic and magnetocaloric properties of manganites La0.5Sr0.5Mn1−m>xm>Crm>xm>O3 (m>xm>=0.05, 0.1, 0.15, and 0.2) have been investigated. The magnetization measurements show that a ferromagnetic cluster behavior is induced by Cr3+ dopants and the paramagnetic to ferromagnetic transition temperature TC decreases from 319 to 251 K with increasing Cr3+ content from 0.05 to 0.2. The positive slope of the Arrott plots near m>Tm>C indicates a second order phase transition. The magnetic entropy change (−Δm>Sm>m>Mm>) is estimated from the isothermal magnetization measurements, and the maximum of the magnetic entropy change (−Δm>Sm>maxm>Mm>) near m>Tm>C shows a power law dependence of magnetic field: −Δm>Sm>maxm>Mm>mmlsi0012" class="mathmlsrc">lass="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0921452616303775&_mathId=si0012.gif&_user=111111111&_pii=S0921452616303775&_rdoc=1&_issn=09214526&md5=1177e9f541b69f95a21b127b3d96d412" title="Click to view the MathML source">=mn(μ0H)lass="mathContainer hidden">lass="mathCode"><math altimg="si0012.gif" overflow="scroll"><mrow><mo>=mo><mi>mmi><msup><mrow><mo stretchy="false">(mo><msub><mrow><mi>μmi>mrow><mrow><mn>0mn>mrow>msub><mi>Hmi><mo stretchy="false">)mo>mrow><mi>nmi>msup>mrow>math> with m>nm> being close to the predicted value ~2/3. The experimental results suggest that the magnetic entropy change and m>Tm>C can be tuned by changing the Cr3+ ions doping level, which offers an effective method for finding an optimal doping level for magnetic refrigeration near room temperature.