Switchable multiple spin states in the Kondo description of doped molecular magnets

We show that introducing electrons in magnetic clusters and molecular magnets lead to rich phase diagrams with a variety of low-spin and high-spin states allowing for multiple switchability. The analysis is carried out for a quantum spin-fermion model using the exact diagonalization, and the cluster mean-field approach. The model is relevant for a number of molecular magnets with triangular motifs consisting of transition metal ions such as Cr, Cu and V. Re-entrant spin-state behavior and chirality on-off transitions exist over a wide parameter regime. A subtle competition among geometrical frustration effects, electron itinerancy, and Kondo coupling at the molecular level is highlighted. Our results demonstrate that electron doping provides a viable mean to tame the magnetic properties of molecular magnets towards potential technological applications

Large shift current in cubic and hexagonal LiZnXX semiconductors

The rectified bulk photovoltaic effect (BPVE) in noncentrosymmetric semiconductors, also called shift current, is considered promising for optooelectronic devices, tetrahertz emission and possibly solar energy harvesting. A clear understanding of the shift current mechanism and search for materials with large shift current is, therefore, of immense interest. $ABC$ semiconductors LiZn$X$ ($X$ = N, P, As and Sb) can be stabilized in cubic as well as hexagonal morphologies lacking inversion symmetry -- an ideal platform to investigate the significant contributing factors to shift current, such as the role of structure and the chemical species. Using density-functional calculations properly accounting for the electronic bandgaps, the shift current conductivities in LiZn$X$ ($X$ = P, As, Sb) are found to be approximately an order of magnitude larger than the well-known counterparts and peak. Notably, hexagonal LiZnSb shows a peak shift current conductivity of $\sim -75 ~\mu$A/V$^2$ and Glass coefficient of $-20$ $\times$ $10$$^{-8}$ cm/V, comparable to highest predicted values in literature. Our comparative analysis reveals a quantitative relationship between the shift current response and the electronic polarization. These findings not only posit Li-Zn-based $ABC$ semiconductors as viable material candidates for potential applications, but also elucidates key aspects of the structure-BPVE relationship

First principles calculation of shift current in chalcopyrite semiconductor ZnSnP2_2

The bulk photovoltaic effect generates intrinsic photocurrents in materials without inversion symmetry. Shift current is one of the bulk photovoltaic phenomena related to the Berry phase of the constituting electronic bands: photo-excited carriers coherently shift in real space due to the difference in the Berry connection between the valence and conduction bands. Ferroelectric semiconductors and Weyl semimetals are known to exhibit such nonlinear optical phenomena. Here we consider chalcopyrite semiconductor ZnSnP$_2$ which lacks inversion symmetry and calculate the shift current conductivity. We find that the magnitude of the shift current is comparable to the recently measured values on other ferroelectric semiconductors and an order of magnitude larger than bismuth ferrite. The peak response for both optical and shift current conductivity, which mainly comes from P-3$p$ and Sn-5$p$ orbitals, is several eV above the bandgap

Publisher Correction: Evolution of electronic and magnetic properties of Sr2IrO4 under strain

In the original version of this Article, all the figures (together with the captions) are inadvertently misplaced. Figures 1, 2, 3, 4, 5, 6 and 7 were wrongly placed in the positions of Figures 7, 1, 2, 3, 4, 5 and 6, respectively. This has been corrected in both the PDF and HTML versions of the Article