CAJ | 학술논문

通过实验和计算的方法研究了Mn2CoMxGa1?x和Mn2CoMxAl1?x (M=Cr, Fe, Co)掺杂系列合金样品.研究发现,在共价作用的影响下, Fe和Co原子占A位,使被取代的MnA (?2.1μB)变成MnD (3.2μB),在最近邻的强交换作用下亚铁磁基体中形成了MnB-CoC-MnD局域铁磁性结构,使分子磁矩的增量最高可达6.18μB. Fe, Co掺杂后建立同样的局域铁磁结构,居里温度的变化趋势却不同.实验观察到Mn2Co1+xAl1?x中掺杂容忍度高达x=0.64,远高于在Mn2CoGa中(x=0.36)的结果;以及随着Al的减少,合金由B2有序向A2混乱转变等现象,为共价作用对合金结构稳定的影响提供了证据.磁测量中发现Cr掺杂后磁矩增量高达3.65μB以及居里温度快速上升的反常现象,意味着对占位规则的违背.
통과실험화계산적방법연구료Mn2CoMxGa1?x화Mn2CoMxAl1?x (M=Cr, Fe, Co)참잡계렬합금양품.연구발현,재공개작용적영향하, Fe화Co원자점A위,사피취대적MnA (?2.1μB)변성MnD (3.2μB),재최근린적강교환작용하아철자기체중형성료MnB-CoC-MnD국역철자성결구,사분자자구적증량최고가체6.18μB. Fe, Co참잡후건립동양적국역철자결구,거리온도적변화추세각불동.실험관찰도Mn2Co1+xAl1?x중참잡용인도고체x=0.64,원고우재Mn2CoGa중(x=0.36)적결과;이급수착Al적감소,합금유B2유서향A2혼란전변등현상,위공개작용대합금결구은정적영향제공료증거.자측량중발현Cr참잡후자구증량고체3.65μB이급거리온도쾌속상승적반상현상,의미착대점위규칙적위배.
The crystal structures and magnetic properties of Mn2CoMxGa1?x and Mn2CoMxAl1?x (M=Cr, Fe, Co) alloys are investigated through experiment and calculation. Due to the covalent effect, the doped Fe and Co atoms preferentially occupy the A sites. It causes that some MnA (?2.1 μB) atoms become MnD (3.2 μB) and a local ferromagnetic structure of MnB-CoC-MnD is generated in the ferrimagnetic matrix, showing that an increment of molecular moment is as high as 6.18 μB. The achievement of the ferromagnetic structure consumes the exchange interaction energy, consequently, reducing the TC in Fe doping alloys. It is found that the toleration for doping Co in Mn2CoAl reaches up to x=0.64, much more than that in Mn2CoGa (x=0.36), and the change from ordered B2 to A2 structures along with the decrease of Al content. These observations reveal the importance of the covalent effect in these intermetallic compounds. The Cr doping shows an abnormal increment of molecular moment of 3.65 μB and increases the TC rapidly, which implies that Cr atoms may take an atomic configuration thereby disobeying to the occupation rule.