Magnetic ordering of Hf3Ni2Si3-type {Sm, Tb, Er}3Co2Ge3 and {Tb, Ho} 3Ni2Ge3 compounds

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:424

Article

Morozkin, A. V.¹  Yapaskurt, V. O.²  Nirmala, R.³  Quezado, S.⁴  Malik, S. K.⁴  Mozharivskyj, Y.⁵  Isnard, O.^6,7 

[1] Moscow MV Lomonosov State Univ, Dept Chem, House 1,Bldg 3,GSP 1, Moscow 119991, Russia

[2] Moscow MV Lomonosov State Univ, Dept Petr, Geol Fac, Moscow 119991, Russia

[3] Indian Inst Technol, Madras 600036, Tamil Nadu, India

[4] Univ Fed Rio Grande do Norte, Dept Fis Teor & Expt, BR-59082970 Natal, RN, Brazil

[5] McMaster Univ, Dept Chem & Chem Biol, 1280 Main St West, Hamilton, ON L8S 4M1, Canada

[6] CNRS, Inst Neel, 25 Rue Martyrs BP166 X, F-38042 Grenoble, France

[7] Univ Grenoble Alpes, Inst Neel, F-38042 Grenoble, France

关键词: Rare-earth compounds;    Magnetic properties;    Magnetocaloric effect;    Neutron diffraction;   

DOI  :  10.1016/j.jmmm.2016.10.036

来源: Elsevier

【 摘 要 】

The magnetic ordering of Hf3Ni2Si3-type {Sm, Tb, Er}(3)Co2Ge3 and {Tb, Ho}(3)Ni2Ge3 compounds (space group Cmcm, oC32) was investigated via magnetization measurements and neutron diffraction study in a zero-applied field. {Sm, Tb, Er}(3)Co2Ge3 and Ho3Ni2Ge3 exhibit field sensitive complex antiferromagnetic orderings with T-N= 51 K, T-m= 10 K for Sm3Co2Ge3, T-N= 34 K, T-m= 13 K for Tb3Co2Ge3, T-N= 7 K for Er3Co2Ge3 and T-N= 11 K for Ho3Ni2Ge3. At 2 K and above the critical field of similar to 5 kOe, 20 kOe, 4 kOe and 7 kOe for Sm3Co2Ge3, Tb3Co2Ge3, Er3Co2Ge3 and Ho3Ni2Ge3, respectively, saturation magnetizations per rare-earth atom are 6.5 mu(B) for Tb3Co2Ge3, 7.0 mu(B) for Er3Co2Ge3 and 8.0 mu(B) for Ho3Ni2Ge3 in the field of 140 kOe, whereas magnetization of Sm3Co2Ge3 has an antiferromagnetic behaviour. The isothermal magnetic entropy change, Delta Sm, indicates a field-induced ferromagnetic ordering in Sm3Co2Ge3, Tb3Co2Ge3, Er3Co2Ge3 and Ho3Ni2Ge3 with a maximal Delta Sm value of -10.9 J/kg K for Ho3Ni2Ge3 at 11 K for a field change of 50 kOe. In a zero-applied magnetic field, below T-N= 33 K and down to T-m (ND)= 15 K Tb3Ni2Ge3 shows an ac-antiferromagnetic ordering with the C2'/c magnetic space group, a K-0=[0, 0, 0] propagation vector and a a(Tb3Ni2Ge3)xb(Tb3Ni2Ge3)xc(Tb3Ni2Ge3) magnetic unit cell. Below T-m (ND)= 15 K, its magnetic structure is a sum of the ac-antiferromagnetic component with the C2'/c magnetic space group of the K-0 vector and a sine-modulated a-antiferromagnetic component of the K-1=[0, 0, +/- 1/3] propagation vector (the magnetic unit cell is a(Tb3Ni2Ge3)xb(Tb3Ni2Ge3)x3c(Tb3Ni2Ge3)). The magnetic structure is made from the 'Tb2 - 2Tb1' clusters of the Tb1 8f and Tb2 4c sublattices with a dominant role of the Tb2 sublattices in the magnetic ordering of Tb3Ni2Ge3.

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