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Eduardo Cisternas

Publications and source records attributed to Eduardo Cisternas.

3 recordsLinked to original sources

Theoretical Characterization of the Magnetic Properties of Vanadium-doped Ti2C MXenes

MXenes are two-dimensional materials composed of transition metals and light elements, known for their high conductivity and versatile surface chemistry. The introduction of spin centers via doping can lead to promising materials for spintronics, magnetic sensing, and data storage. We study the effect of V doping in Ti2C using first principle and Monte-Carlo simulations. Our results show that pristine Ti2C exhibits ferromagnetic intralayer and antiferromagnetic interlayer exchange interactions, yielding an antiferromagnetic ground state. Vanadium incorporation alters these couplings, yet all doped configurations - Ti7VC4 and three Ti6V2C4 variants - retain predominantly antiferromagnetic order. Despite the preserved ground state, V doping enhances the magnetic response, most notably in the p-Ti6V2C4 configuration, which displays increased low-field susceptibility and partial spin alignment across layers. As experimentally isolating individual doped phases is unlikely, samples will consist of mixed configurations whose collective behavior nonetheless exhibits clear signatures of V-induced magnetic modification. These results reveal how transition-metal substitution tunes exchange interactions in MXenes and offer guidance for engineering their magnetic functionalities.

cond-mat.mtrl-sci

Quasinormal modes and greybody factors of a four-dimensional Lifshitz black hole with z=0

We study scalar perturbations for a four-dimensional asymptotically Lifshitz black hole in conformal gravity with dynamical exponent z=0, and spherical topology for the transverse section, and we find analytically and numerically the quasinormal modes for scalar fields for some special cases. Then, we study the stability of these black holes under scalar field perturbations and the greybody factors.

gr-qc

Dirac quasinormal modes for a 4-dimensional Lifshitz Black Hole

We study the quasinormal modes of fermionic perturbations for an asymptotically Lifshitz black hole in 4-dimensions with dynamical exponent z=2 and plane topology for the transverse section, and we find analytically and numerically the quasinormal modes for massless fermionic fields by using the improved asymptotic iteration method and the Horowitz-Hubeny method. The quasinormal frequencies are purely imaginary and negative, which guarantees the stability of these black holes under massless fermionic field perturbations. Remarkably, both numerical methods yield consistent results; i.e., both methods converge to the exact quasinormal frequencies; however, the improved asymptotic iteration method converges in a fewer number of iterations. Also, we find analytically the quasinormal modes for massive fermionic fields for the mode with lowest angular momentum. In this case, the quasinormal frequencies are purely imaginary and negative, which guarantees the stability of these black holes under fermionic field perturbations. Moreover, we show that the lowest quasinormal frequencies have real and imaginary parts for the mode with higher angular momentum by using the improved asymptotic iteration method.

gr-qc