Ca掺杂双钙钛矿锰氧化物La_2NiMnO_6的物性研究
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摘要
通过磁化强度随温度变化曲线(M-T)和等温磁化曲线(M-H)可判定随着Ca的掺杂,系统的铁磁性减弱、反铁磁性增强;两样品的磁滞回线和2 K下磁滞回线的放大图可以说明Ca的掺杂对系统反位无序度的影响不大,但会导致系统的反相边界增加,反铁磁耦合增强;磁化率倒数随温度变化曲线χ~(-1)-T向上背离C-W定律,掺Ca后向上背离更明显,说明Ca掺杂增强了长程铁磁有序;最后我们讨论了系统磁熵和电性变化,同时阐述了Ca的掺杂使系统经历了弱一级相变。
From temperature dependence of magnetization in a magnetic field of 5 mT(M-T) and field-dependent magnetization near Curie-temperature(M-H) for La_(2-x)Ca_xNiMnO_6(x=0, 0.1), it can be determined that with the doping of Ca, the ferromagnetism of the system was weakened and the antiferromagnetism was enhanced. The Hysteresis loops and the enlarged view of the low-field hysteresis loops at 2 K under the FC process with a cooling field of 1 T for La_(2-x)Ca_xNiMnO_6(x=0, 0.1) indicated that the doping of Ca had little effect on the disorder degree of the samples, but Ca-doped could increase the anti-phase boundaries and antiferromagnetic coupling of the samples. Temperature dependent inverse magnetic susceptibility(χ~(-1)) under 5 mT for La_(2-x)-Ca_xNiMnO_6(x=0, 0.1) showed upward deviation from CW law. With Ca-doping, the degree of deviation was more obvious, indicating that Ca-doping enhanced long-range ferromagnetic order. Finally, the magnetic entropy of the samples was discussed and it could be explained that Ca-doping made the samples experienced a weak first-order phase change.
From temperature dependence of magnetization in a magnetic field of 5 mT(M-T) and field-dependent magnetization near Curie-temperature(M-H) for La_(2-x)Ca_xNiMnO_6(x=0, 0.1), it can be determined that with the doping of Ca, the ferromagnetism of the system was weakened and the antiferromagnetism was enhanced. The Hysteresis loops and the enlarged view of the low-field hysteresis loops at 2 K under the FC process with a cooling field of 1 T for La_(2-x)Ca_xNiMnO_6(x=0, 0.1) indicated that the doping of Ca had little effect on the disorder degree of the samples, but Ca-doped could increase the anti-phase boundaries and antiferromagnetic coupling of the samples. Temperature dependent inverse magnetic susceptibility(χ~(-1)) under 5 mT for La_(2-x)-Ca_xNiMnO_6(x=0, 0.1) showed upward deviation from CW law. With Ca-doping, the degree of deviation was more obvious, indicating that Ca-doping enhanced long-range ferromagnetic order. Finally, the magnetic entropy of the samples was discussed and it could be explained that Ca-doping made the samples experienced a weak first-order phase change.
引文
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[2] Wang Wenqing,Xiang Junyou,Wu Kehan,et al.Magnetic properties of the doped perovskite cobalt oxides La0.5-xNdxSr0.5CoO3[J].Rare Earths,2015,36(6):39-44(in Chinese).王文清,向俊尤,武柯含,等.钙钛矿钴氧化物La0.5-xNdxSr0.5CoO3(x=0,0.1,0.15)的磁性[J].稀土,2015,36(6):39-44.
[3] Zhou S M,Shi L,Yang H P,et al.Evidence of short-range magnetic ordering above TC in the double perovskite La2NiMnO6[J].Applied Physics Letters,2007,91(17):172505.
[4] Mandal P R,Nath T K.Evolution of Griffith phase in hole doped double perovskite La2-xSrxCoMnO6 (x=0.0,0.5,and 1.0)[J].Materials Research Express,2015,6(2):066101.
[5] Guo Y Q,Shi L,Zhou S M,et al.Near room-temperature magnetoresistance effect in double perovskite La2NiMnO6[J].Applied Physics Letters,2013,102(22):222401.
[6] Wang X J,Sui Y,Li Y,et al.The influence of the antiferromagnetic boundary on the magnetic property of La2NiMnO6[J].Applied Physics Letters,2009,95(25):252502.
[7] García-Hernández M,Martínez J L,Martínez-Lope M J,et al.Finding universal correlations between cationic disorder and low field magnetoresistance in FeMo double perovskite series[J].Physical Review Journals,2001,86(11):2443.
[8] Sarma D D,Ray S,Tanaka K,et al.Intergranular magnetoresistance in Sr2FeMoO6from a magnetic tunnel barrier mechanism across grain boundaries[J].Physical Review Letters,2007,98(15):157205.
[9] Zhao S Y,Shi L,Zhou S M,et al.Size-dependent magnetic properties and Raman spectra of La2NiMnO6 nanoparticles[J].Applied Physics,2009,106(19):123901.
[10] Guo H Z,Burgess J,Ada E,et al.Influence of defects on structural and magnetic properties of multifunctional La2NiMnO6 thin films[J].Physical Review B,2008,77(17):174423.
[11] Truong K D,Laverdière J,Singh M P,et al.Impact of Co/Mn cation ordering on phonon anomalies in La2CoMnO6 double perovskites:Raman spectroscopy[J].Physical Review B,2007,76(13):132413.
[12] Sun Xiaodong,Xyu Bao,Wu Hongye,et al.Magnetic entropy change and electrical transport properties of rare earth Tb doped manganites La4/3Sr5/3Mn2O7[J].Acta Physical Sinica,2017,66(15):245-252(in Chinese).孙晓东,徐宝,吴鸿业,等.Tb掺杂双层锰氧化物La4/3Sr5/3Mn2O7的磁熵变和电输运性质[J].物理学,2017,66(15):245-252.
[13] Nirmala R,Mudryk Y,Pecharsky V K,et al.Unusual magnetism of Er0.75Dy0.25Al2R[J].Physical Review B,2007,76(1):014407.
[14] Zemni S,Bassaoui M,Dhahri J,et al.Above room temperature magnetocaloric effect in perovskite Pr0.6Sr0.4MnO3[J].Materials Letters,2009,63(3-4):489-491.
[15] Shi Qianyi,Xu Shujuan,Ju Jinghua,et al.Low-field giant magnetocaloric effect in (Dy1-xYx)Co2 alloys[J].Journal of Changshu Institute of Technology (Natural Sciences),2015,29(2):59-62 (in Chinese) .史倩仪,许淑娟,居晶华,等.(Dy1-xYx)Co2合金的低场巨磁热效应[J].常熟理工学院学报(自然科学),2015,29(2):59-62.
[16] Yun Huiqin,Xing Ru,Sun Xiaodong,et al.Study on magnetic and electrical properties of double provskite manganese oxides (La1-xEux)4/3Sr5/3Mn2O7(x=0.0,0.1,0.2)[J].Chinese Journal of Low Temperature Physics,2017,39(2):11-15(in Chinese).云慧琴,邢茹,孙晓东.双层钙钛矿锰氧化物(La1-xEux)4/3Sr5/3MnO3(x=0.0,0.1,0.2)的磁性和电输运性质研究[J].低温物理学报,2017,39(2):11-15.