Ferromagnetic MnCoGe thin films produced via magnetron sputtering and non-diffusive reaction

Portavoce, A.; Assaf, Elie; Alvarez, Carlos; Bertoglio, M.; Clérac, Rodolphe; Hoummada, K.; Alfonso, Claude; Charaı̈, A.; Pilone, O.; Hahn, Konstanze R.; Dolocan, Voicu; Bertaina, Sylvain

doi:10.1016/j.apsusc.2017.12.151

Cited by 16 publications

(14 citation statements)

References 61 publications

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“…A stable hexagonal phase of MnCoGe thin films at room temperature has been observed in experiments carried out in our laboratory. 44 The reason for the hexagonal phase to be stable at room temperature, however, is not resolved yet. This in mind, we have analyzed the differences in the thermodynamic equilibrium of the hexagonal and the orthorhombic phase of MnCoGe with various compositions.…”

Section: ■ Computational Methodsmentioning

confidence: 99%

Structural and Composition Effects on Electronic and Magnetic Properties in Thermoelectric Mn_1–x–yCo_1+xGe_1+y Materials

et al. 2017

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Magnetocaloric effects are of great interest for magnetic refrigeration as well as thermomagnetic energy production. Materials based on MnCoGe have been shown to be promising candidates in this respect. In this study, structural, electronic, and magnetic properties of MnCoGe alloys with several compositions (stoichiometric and Mn-depleted) have been investigated using first-principles calculations based on density functional theory. Their stability in the orthorhombic and hexagonal structure has been determined for different spin configurations. In all materials, the ferromagnetic orthorhombic phase is most stable; however, variation of the composition can lead to a decrease of the energy difference between the equilibrium orthorhombic and hexagonal structure. The magnetic moment is primarily found on the Mn atoms leading to a decrease of the total magnetic moment with decreasing amount of Mn. Using the Boltzmann transport model and the electronic density of states, the spin Seebeck coefficient has been estimated. At room temperature, it is found to be highest in stoichiometric MnCoGe in the orthorhombic crystal structure.

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Section: ■ Computational Methodsmentioning

confidence: 99%

Structural and Composition Effects on Electronic and Magnetic Properties in Thermoelectric Mn_1–x–yCo_1+xGe_1+y Materials

et al. 2017

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“…Firstly, the hexagonal B8 2 phase was obtained at room temperature after annealing at T = 500 • C and remained in this phase upon cycling down to low temperature, consistent with other reports of sputtered MnCoGe films. 16 Secondly, the films display ferrimagnetic rather than ferromagnetic order reported in other investigations of this material. We support the analysis of the magnetic properties with DFT calculations that show the spins from Mn-antisite defects align in the opposite direction to the spins on the Mn-sites.…”

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confidence: 55%

Disorder-induced ferrimagnetism in sputtered Mn$_{x}$CoGe thin films

Kalliecharan¹,

McCoombs²,

Cormier³

et al. 2019

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Investigations into the magnetic properties of sputtered MnxCoGe films in the range 0.8 ≤ x ≤ 2.5 uncovered ferrimagnetic order, unlike the ferromagnetic order reported in bulk samples. These films formed hexagonal Ni2In-type structures in all measured compositions. While the Curie temperatures of the films are comparable to those of hexagonal bulk MnCoGe, there is a reduction in the magnetization of the MnxCoGe film relative to bulk MnCoGe, and a magnetization compensation point is observed in the x < 1 samples. To understand the behavior, we calculated the magnetic moments of Mn-antisite defects in MnCoGe with density-function theory calculations. Models constructed from the calculation suggest that films become ferrimagnetic due to the presence of Mn on the Co and Ge sites. In the x < 1 samples, these defects arose from the disorder in the films, whereas for x > 1, the excess Mn was driven onto the antisites and produced ferrimagnetic order.

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“…A Co–Mn–Ge thin film produced by Portavoce et al fits into this composition space . According to their investigation, the annealed thin film exhibits the CoMnGe (HT) phase.…”

Section: Resultsmentioning

confidence: 96%

“…A Co−Mn−Ge thin film produced by Portavoce et al fits into this composition space. 21 According to their investigation, the annealed thin film exhibits the CoMnGe (HT) phase. However, the diffraction data presented in the manuscript hints at the presence of the Co 2 MnGe as well.…”

Section: ■ Resultsmentioning

confidence: 99%

“…These MLs (Co–Mn–Ge and Co–Mn–Ge–Si) cover a wide compositional range around the 1:1:1 stoichiometry of Co, Mn, and Ge. The MLs were compared to each other and prior research on Co–Mn–Ge thin films , to investigate the existence range of the CoMnGe phase in Co–Mn–Ge–Si. Furthermore, the magnetic properties and the structural transition properties of selected regions in the latter ML were analyzed.…”

Section: Introductionmentioning

confidence: 99%

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Influences of Si Substitution on Existence, Structural and Magnetic Properties of the CoMnGe Phase Investigated in a Co–Mn–Ge–Si Thin-Film Materials Library

et al. 2019

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Materials exhibiting a giant magnetocaloric effect (GMCE) need to be finely tuned with respect to their magnetic and structural properties, specifically their respective transition temperatures. Co−Mn−Ge and Co−Mn−Ge−Si thin-film materials libraries (MLs) were fabricated and characterized to determine the composition range in which the CoMnGe phase is stable and analyze selected single-phase measurement regions. Phase analysis was performed on these MLs and refined in regard to the CoMnGe single-phase region by synchrotron diffraction experiments. A comparison of the MLs revealed that the CoMnGe (HT) single-phase region gets smaller with the addition of Si and exists for 26.5 at. % < Co < 29.5 at. %, 34 at. % < Mn < 37 at. %, Ge ∼ 35 at. %, and Si ∼ 1.5 at. % in the quaternary ML. The investigation of magnetic and structural transition properties in this region revealed hard-magnetic behavior with Curie temperatures (T c ) between 261 and 274 K and large hysteresis widths with values >100 K for the structural transition. A low Co content was necessary to achieve an overlap of T c and structural transition temperatures, leading to the most favorable properties for a GMCE to be found in Co 26.

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Ferromagnetic MnCoGe thin films produced via magnetron sputtering and non-diffusive reaction

Cited by 16 publications

References 61 publications

Structural and Composition Effects on Electronic and Magnetic Properties in Thermoelectric Mn_1–x–yCo_1+xGe_1+y Materials

Structural and Composition Effects on Electronic and Magnetic Properties in Thermoelectric Mn_1–x–yCo_1+xGe_1+y Materials

Disorder-induced ferrimagnetism in sputtered Mn$_{x}$CoGe thin films

Influences of Si Substitution on Existence, Structural and Magnetic Properties of the CoMnGe Phase Investigated in a Co–Mn–Ge–Si Thin-Film Materials Library

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Ferromagnetic MnCoGe thin films produced via magnetron sputtering and non-diffusive reaction

Cited by 16 publications

References 61 publications

Structural and Composition Effects on Electronic and Magnetic Properties in Thermoelectric Mn1–x–yCo1+xGe1+y Materials

Structural and Composition Effects on Electronic and Magnetic Properties in Thermoelectric Mn1–x–yCo1+xGe1+y Materials

Disorder-induced ferrimagnetism in sputtered Mn$_{x}$CoGe thin films

Influences of Si Substitution on Existence, Structural and Magnetic Properties of the CoMnGe Phase Investigated in a Co–Mn–Ge–Si Thin-Film Materials Library

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Structural and Composition Effects on Electronic and Magnetic Properties in Thermoelectric Mn_1–x–yCo_1+xGe_1+y Materials

Structural and Composition Effects on Electronic and Magnetic Properties in Thermoelectric Mn_1–x–yCo_1+xGe_1+y Materials