arXiv subjects

Shuang Jia

Publications and source records attributed to Shuang Jia.

111 records · Page 7Linked to original sources

arXiv2009

Lattice collapse and the magnetic phase diagram of Sr$_{1-x}$Ca$_x$Co$_2$P$_2$

We report that the 122 type Sr$_{1-x}$Ca$_x$Co$_2$P$_2$ solid solution undergoes an anomalous structural transition from the uncollapsed to the collapsed ThCr$_2$Si$_2$ structure at a distinct onset composition near $x=0.5$. Correlated with the structural changes, the electronic system evolves from a nearly ferromagnetic Fermi liquid to an antiferromagnetic metal, through a complex crossover regime. The structural collapse, driven by P-P bonding across the (Sr,Ca) layers, is much more pronounced in this system than it is in the analogous Fe-based system, indicating a strong sensitivity of structure to total electron count in the transition metal pnictide 122 family.

cond-mat.str-el↗

arXiv2009

Magnetic properties of RFe$_2$Zn$_{20}$ and RCo$_2$Zn$_{20}$(R = Y, Nd, Sm, Gd - Lu)

Magnetization, resistivity and specific heat measurements were performed on single crystals of RFe$_2$Zn$_{20}$ and RCo$_2$Zn$_{20}$(R = Y, Nd, Sm, Gd - Lu). Whereas LuCo$_2$Zn$_{20}$ and YCo$_2$Zn$_{20}$ manifest unremarkable, metallic behavior, LuFe$_2$Zn$_{20}$ and YFe$_2$Zn$_{20}$ manifest behaviors characteristic of nearly ferromagnetic Fermi liquids. When the well defined $4f$ local moments (Gd$^{3+}$ - Tm$^{3+}$) were embedded into this strongly polarizable host, they all manifest enhanced, ferromagnetic ordering and the values of $T_{\mathrm{C}}$ for RFe$_2$Zn$_{20}$ (R = Gd - Tm) scale with the de Gennes factor. In addition, the data on the RFe$_2$Zn$_{20}$ compounds indicate a small crystal electronic field (CEF) effect, compare with the interaction energy scale. On the other hand, the local moment bearing members of RCo$_2$Zn$_{20}$ (R = Nd, Sm, Gd - Tm) manifest weak magnetic interactions and the magnetic properties for R = Dy - Tm members are strongly influenced by the CEF effect on the R ions. The magnetic anisotropy and specific heat data for the Co series were used to determine the CEF coefficient of R ion in the cubic coordination. These CEF coefficients, determined for the Co series, are consistent with the magnetic anisotropy and specific heat data for the Fe series, which indicates similar CEF effects for the Fe and Co series. Such analysis, combined with specific heat and resistivity data, indicates that for R = Tb - Ho, the CEF splitting scale is smaller than their $T_{\mathrm{C}}$ values, whereas for ErFe$_2$Zn$_{20}$ and TmFe$_2$Zn$_{20}$ the $4f$ electron loses part of its full Hund's rule ground state degeneracy above $T_{\mathrm{C}}$. YbFe$_2$Zn$_{20}$ and YbCo$_2$Zn$_{20}$ manifest typical, but distinct heavy Fermion behaviors associated with different Kondo temperatures.

cond-mat.str-el↗

arXiv2007

Variation of the magnetic ordering in GdT$_2$Zn$_{20}$ (T= Fe, Ru, Os, Co, Rh and Ir) and its correlation with the electronic structure of isostructural YT$_2$Zn$_{20}$

Magnetization, resistivity and specific heat measurements were performed on the solution-grown, single crystals of six GdT$_2$Zn$_{20}$ (T = Fe, Ru, Os, Co, Rh and Ir) compounds, as well as their Y analogues. For the Gd compounds, the Fe column members manifest a ferromagnetic (FM) ground state (with an enhanced Curie temperature, $T_{\mathrm{C}}$, for T = Fe and Ru), whereas the Co column members manifest an antiferromagnetic (AFM) ground state. Thermodynamic measurements on the YT$_2$Zn$_{20}$ revealed that the enhanced $T_{\mathrm{C}}$ for GdFe$_2$Zn$_{20}$ and GdRu$_2$Zn$_{20}$ can be understood within the framework of Heisenberg moments embedded in a nearly ferromagnetic Fermi liquid. Furthermore, electronic structure calculations indicate that this significant enhancement is due to large, close to the Stoner FM criterion, transition metal partial density of states at Fermi level, whereas the change of FM to AFM ordering is associated with filling of electronic states with two additional electrons per formula unit. The degree of this sensitivity is addressed by the studies of the pseudo-ternary compounds Gd(Fe$_x$Co$_{1-x}$)$_2$Zn$_{20}$ and Y(Fe$_x$Co$_{1-x}$)$_2$Zn$_{20}$ which clearly reveal the effect of 3d band filling on their magnetic properties.

cond-mat.str-el↗