Phase separation, low-temperature transport and magnetic response of Ce-Al (Ga) metallic glasses

(Oral talk at the MSE 2024 conference in Darmstadt, Germany, September 2024) In recent years, much attention has been given to phase separated metallic glasses (MGs) which offer a unique opportunity to develop alloys or composites with hierarchical microstructure at various length scales. The structure and physical properties of phase separated MGs have characteristics different from those of other MGs [1, 2]. Many efforts are made to understand the origin of phase separation in MGs by proposing mechanisms e.g. nucleation and growth, spinodal decomposition [1, 3]; yet the understanding of the mechanism is insufficient. In this presentation, we will discuss the findings of our recent research on the role of Ga substitution in place of Al in Ce-Al (Ga) MGs in order to comprehend the origin of phase separation. The enthalpy of mixing of the three possible binaries in this system was not able to provide an explanation for phase separation. The X-ray absorption spectroscopy (XAS) spectra of Ce-based melt-spun ribbons revealed the presence of 4f0 delocalized states of Ce atoms in Ga substituted alloys. The chemical pressure effect due to Ga substitution has caused the shortening of Ce-Ce distance in the alloys, resulting in the formation of two distinct main clusters (Figure 1), namely Low Density Clusters (LDC) and High Density Clusters (HDC). It has been studied, how the change in the electronic structure of Ce and microstructural variations resulting due to phase separation in Ce-Al (Ga) MGs affects their low temperature transport properties [4]. With Ga substitution, a magnetic field tuned magnetoresistance transition from positive to negative values has been observed at around 2.45 T. Thus, this work provides a new way for research in delineating issues related to phase separation in amorphous systems. References[1] D.H. Kim, W.T. Kim, E.S. Park, N. Mattern, J. Eckert, Prog. Mater. Sci., 2013, 58, 1103-1172.[2] G. Wu, S. Liu, Q. Wang, J. Rao, W. Xia et al., Nat. Commun., 2023, 14, 3670[3] Z.D. Wu, X.H. Lu, Z.H. Wu, H.W. Kui, J. Non-Cryst. Solids, 2014, 385, 40-46.[4] D. Singh, D. Singh, O.N. Srivastava, R.S. Tiwari, Scr. Mater., 2016, 118, 24-28.