arXiv subjects

C. Y. Jiang

Publications and source records attributed to C. Y. Jiang.

5 recordsLinked to original sources

arXiv2024

Evolution of magnetism in Ruddlesden-Popper bilayer nickelate revealed by muon spin relaxation

Here we report the positive muon spin relaxation study on Pr-doped La$_{1.9}$Pr$_{1.1}$Ni$_2$O$_{6.97}$ and oxygen-deficient La$_3$Ni$_2$O$_{6.63}$ polycrystalline under ambient pressure. Zero-field $μ^+$SR experiments reveal the existence of bulk long-range magnetic order in La$_{1.9}$Pr$_{1.1}$Ni$_2$O$_{6.97}$ with $T_{N}=161\ \rm{K}$, while La$_3$Ni$_2$O$_{6.63}$ exhibits a short-range magnetic ground state with $T_N=30\ \rm{K}$. The magnetic transition width of La$_{1.9}$Pr$_{1.1}$Ni$_2$O$_{6.97}$ revealed by weak-transverse-field $μ^+$SR is narrower compared to La$_3$Ni$_2$O$_{6.92}$. Our $μ^+$SR experiment results provide a comprehensive view on the correlation between magnetism and structure perfection in Ruddlesden-Popper bilayer nickelates under ambient pressure.

cond-mat.str-el↗

arXiv2024

Persistent Spin Dynamics in the Ising Triangular-lattice Antiferromagnet Ba$_6$Nd$_2$Ti$_4$O$_{17}$

We report results of magnetic susceptibility, specific heat, and muon spin relaxation ($μ$SR) measurements on the polycrystalline Ba$_6$Nd$_2$Ti$_4$O$_{17}$, a disorder-free triangular-lattice antiferromagnet. The absence of long-range magnetic order or spin freezing is confirmed down to 30~mK, much less than the Curie-Weiss temperature -1.8~K. The magnetic and specific heat measurements reveal the effective-1/2 spins are Ising-like. The persistent spin dynamics is determined down to 37~mK. Our study present a remarkable example of Ising spins on the triangular lattice, which remains magnetically disordered at low temperatures and potentially hosts a quantum spin liquid ground state.

cond-mat.str-el↗

arXiv2022

Spin excitations in the quantum dipolar magnet Yb(BaBO$_3$)$_3$

We report results of magnetization, specific-heat and muon-spin relaxation measurements on single crystals of disorder-free Yb$^{3+}$ triangular lattice Yb(BaBO$_3$)$_3$. The magnetization experiments show anisotropic magnetic properties with Curie-Weiss temperatures $θ_{\perp}=-1.40$~K ($H \perp c$) and $θ_{\parallel}=-1.16$~K ($H \parallel c$) determined from low temperature data. The absence of both long-range antiferromagnetic order and spin freezing is confirmed down to 0.27 K at zero field. A two-level Schottky anomaly due to the opening of the ground-state Kramers doublet is observed from the low-temperature specific-heat measurements when the applied magnetic fields $μ_0H >0.7$~T. At zero field, the increase of both $C_{\rm mag}/T$ and the muon spin relaxation rate $λ$ below 1~K is due to the electronic spin excitations, which often exist in quantum magnets where dipole-dipole interaction creates an anisotropy of magnetic properties. The spin excitation is also supported by the unusual maximum of field dependence of $λ$ due to the field-induced increase of the density of excitations. We argue that dipolar interaction is dominant and induces the spin dynamics in the quantum magnet Yb(BaBO$_3$)$_3$.

cond-mat.str-el↗

arXiv2009

Influence of baryonic physics on the merger time-scale of galaxies in N-body/hydrodynamical simulations

Following our previous work(Jiang et al.(2008)), in which we studied the merger time-scale of galaxies in a high-resolution cosmological hydro/N-body simulation, we investigate the potential influence of uncertainties in the numerical implementation of baryonic physics on the merger time-scale. The simulation used in the previous work suffers from the overcooling problem which causes the central galaxies of large halos too massive. This may result in a shortened merger time-scale compared to that in the real universe. We run a similar simulation, but the stellar mass is significantly reduced to model another extreme case of low stellar mass. Our result shows that the merger time-scale is little affected by the star formation recipes, except for the satellites in nearly radial orbits which show a 22 percent higher time-scale in the lower stellar mass case. Since the radial orbits only account for a small part of the satellites' orbits, the fitting formula in Jiang et al.(2008) is still applicable to a reasonable accuracy, nearly immune to the uncertainty in the baryonic physics.

astro-ph.CO↗

arXiv2007

A fitting formula for the merger timescale of galaxies in hierarchical clustering

We study galaxy mergers using a high-resolution cosmological hydro/N-body simulation with star formation, and compare the measured merger timescales with theoretical predictions based on the Chandrasekhar formula. In contrast to Navarro et al., our numerical results indicate, that the commonly used equation for the merger timescale given by Lacey and Cole, systematically underestimates the merger timescales for minor mergers and overestimates those for major mergers. This behavior is partly explained by the poor performance of their expression for the Coulomb logarithm, \ln (m_pri/m_sat). The two alternative forms \ln (1+m_pri/m_sat) and 1/2\ln [1+(m_pri/m_sat)^2] for the Coulomb logarithm can account for the mass dependence of merger timescale successfully, but both of them underestimate the merger time scale by a factor 2. Since \ln (1+m_pri/m_sat) represents the mass dependence slightly better we adopt this expression for the Coulomb logarithm. Furthermore, we find that the dependence of the merger timescale on the circularity parameter εis much weaker than the widely adopted power-law ε^{0.78}, whereas 0.94*ε^{0.60}+0.60 provides a good match to the data. Based on these findings, we present an accurate and convenient fitting formula for the merger timescale of galaxies in cold dark matter models.

astro-ph↗