Magnetocaloric effect of ball-milled CoMn0.95V0.05Ge nano-powders

We have studied the magnetic properties and magnetocaloric effect of ball milled CoMn0.95V0.05Ge alloy by means of temperature and field dependence of magnetisation measurements. CoMn0.95V0.05Ge nano-powders with different particle size distribution were prepared by varying the milling time for 4, 6 and 8 h. The atomic force microscopy (AFM) images showed that the average size of the particles decreases with increased milling time as expected. The nature of the magnetic phase transition has been determined by using Arrott plots, rescaled magnetic entropy change and power exponents of ?SM. We found that the nature of the magnetic transition for nano powders has a second order nature, although their bulk counterpart with same composition exhibits a first order magnetostructural phase transition. The observed maximum magnetic entropy change for nano powders is, therefore, slightly lower than that of their bulk counterparts. However a 50 % increasing of relative cooling power for nano-powders is achieved. These results suggest that CoMn0.95V0.05Ge nano-powders could be a suitable candidate as working substance for magnetic cooling technology around room temperature. © 2020 Elsevier B.V.109T743This work was supported by TUBITAK (Project Number: 109T743)

Structure and giant inverse magnetocaloric effect of epitaxial Ni-Co-Mn-Al films - Conference Paper

2015 IEEE International Magnetics Conference, INTERMAG 2015 -- 11 May 2015 through 15 May 2015 -- -- 113931In the ongoing search for magnetocaloric materials, Heusler compound based ferromagnetic shape memory alloys (FSMA) of the system Ni-Mn-Z (Z=Sb, Ga, In, Sn) turned out to be very promising due to low cost of the containing elements and sizable magnetocaloric effects (MCE).[1] Substitution of Ni against Co in Ni-Mn-Z is known to improve the metamagnetic behavior of the martensitic transition, and thus the magnetocaloric properties as it increases the austenite Curie temperature TCA and leads to a transition from weak magnetic martensite to ferromagnetic austenite. Off-stoi-chiometric Ni-Mn-Al also shows a martensitic transition but accompanied by only small changes in the magnetization and hence neglectable MCE.[2] Substitution of up to 10at.% Co for Ni strongly promotes the ferromagnetism in the austenite phase and leads to a metamagnetic martensitic transition.[3] The magnetization difference between austenite and martensite enables magnetic field induced reverse transition together with an inverse magnetocaloric effect. © 2015 IEEE

Thickness-Dependent Permanent Magnet Properties of ZrCo Thin Films Grown on Si with Pt Underlayer

Yuzuak GD, Yuzuak E, Teichert N, Hütten A, Elerman Y. Thickness-Dependent Permanent Magnet Properties of ZrCo Thin Films Grown on Si with Pt Underlayer. METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE. 2017;48A(5):2654-2659.Zr-Co is one of the essential magnetic materials due to its interesting magnetic and structural properties. In this work, we studied the magnetic and structural properties of ZrCo thin films of different thicknesses grown on Si substrate with Pt underlayer. The structural properties and chemical composition of the ZrCo films were investigated by X-ray diffraction analysis, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analysis, and atomic force microscopy-magnetic force microscopy measurements. The saturation magnetization, M(H) characteristic, and Henkel plots of the Zr-Co films were obtained by vibrating-sample magnetometry. The results show that and were enhanced with decreasing layer thickness of Zr-Co. For 10-nm ZrCo with 20-nm Pt underlayer thin film, we observed coercive field of 2 kOe with energy product of 0.7 MGOe. Our results may be valuable for use of ZrCo thin films in nanomagnet applications