Co-doped ${\mathrm{MnNiGe}}_{1.05}$ alloys of nominal compositions ${\mathrm{MnNi}}_{1-x}{\mathrm{Co}}_x{\mathrm{Ge}}_{1.05}$ (for $x=0.075$ and 0.125), with a significant amount of vacancies at the transition-metal sites, have been explored through temperature-dependent structural and magnetic investigations. Such studies confirm the presence of martensitic phase transition (MPT) in both the alloys. However, the observed MPT is found to be incomplete in nature. The presence of a significant amount of high-temperature austenite phase, well below the MPT, results in several interesting features, including field-induced metamagnetic transition and nonmonotonic change in the inverse magnetocaloric behavior, etc. In addition, a possible spin-reorientation transition has also been noticed in the magnetically ordered austenite phase for both the alloys.

中文翻译：

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不完全马氏体相变对Co掺杂MnNiGe1.05合金磁行为的影响

共掺杂${\mathrm{锰镍锗}}_{1.05}$标称成分合金${\mathrm{锰镍}}_{1-X}{钴}_X{锗}_{1.05}$（为了$X=0.075$和0.125），在过渡金属位点有大量空位，已通过温度依赖性结构和磁性研究进行了探索。这些研究证实了两种合金中都存在马氏体相变（MPT）。然而，观察到的 MPT 本质上是不完整的。远低于 MPT 的大量高温奥氏体相的存在导致了一些有趣的特征，包括场诱导的变磁转变和逆磁热行为的非单调变化等。此外，可能存在自旋重定向转变在这两种合金的磁序奥氏体相中也注意到了这一点。