Jennifer Trinh, PhD
Quantum Criticality Among Entangled Spin Chains
Authors: Blanc, N.*, Trinh, J.*, Dong, L., Bai, X., Aczel, A., Mourigal, M., Balents, L., Siegrist, T., Ramirez, A.P.
*contributed equally
Abstract:
In conventional antiferromagnets, an increasing magnetic field progressively quenches staggered order. On approaching the quantum critical point, the transverse field component of the order also vanishes, even at zero temperature, and the specific heat (C) signature becomes very weak. Here we present C measurements of the S = 1/2 quasi-1D antiferromagnet K2PbCu(NO2)6, across the temperature (T) and field (H) boundary between 3D order and the paramagnetic phase. At this boundary, C/T exhibits a large peak, the magnitude of which extrapolates to a finite value at T = 0, suggestive of a spinon Sommerfeld coefficient. This anomaly demonstrates an H-induced shift of entropy from 1D correlations to 3D quantum critical fluctuations.
Links: https://www.nature.com/articles/s41567-017-0010-y.pdf
Thermodynamic Measurement of Angular Anisotropy at the Hidden Order Transition of URu2Si2
Authors: Trinh, J., Bruck, E., Siegrist, T., Flint, R., Chandra, P., Coleman, P., Ramirez, A.P.
Abstract:
The heavy fermion compound URu2Si2 continues to attract great interest due to the unidentified hidden order it develops below 17.5K. The unique Ising character of the spin fluctuations and low temperature quasiparticles is well established. We present detailed measurements of the angular anisotropy of the nonlinear magnetization that reveal a (cosθ)^4 Ising anisotropy both at and above the ordering transition. With Landau theory, we show this implies a strongly Ising character of the itinerant hidden order parameter.
Links:
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.157201
Magnetic Groundstates of the Rare-Earth Tripod Kagome Lattice
Authors: Dun, Z.L., Trinh, J., Li, K., Lee, M., Chen, K., Baumbach, R., Hu, Y., Wang, Y.X., Choi, E.S., Shastry, B.S., Ramirez, A.P., Zhou, H.D.
Abstract:
We present the structural and magnetic properties of a new compound family, Mg2RE3Sb3O14 (RE=Gd,Dy,Er), with a hitherto unstudied frustrating lattice, the “tripod kagome" structure. Susceptibility (ac, dc) and specific heat exhibit features that are understood within a simple Luttinger-Tisza-type theory. For RE=Gd, we found long-ranged order (LRO) at 1.65 K, which is consistent with a 120° structure, demonstrating the importance of diople interactions for this 2D Heisenberg system. For RE=Dy, LRO at 0.37 K is related to the “kagome spin ice” physics for a 2D system. This result shows that the tripod kagome structure accelerates the transition to LRO predicted for the related pyrochlore systems. For RE=Er, two transitions, at 80 mK and 2.1 K are observed, suggesting the importance of quantum fluctuations for this putative XY system.
Links:
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.157201
https://arxiv.org/abs/1601.01575
New paper:
The Young Exoplanet Initiative (YETI)
Authors: Neuhäuser, R. et al. (+Trinh, J.)
Abstract (abridged):
We present the Young Exoplanet Transit Initiative (YETI), in which we use several 0.2 to 2.6-m telescopes around the world to monitor continuously young (≤100 Myr), nearby (≤1 kpc) stellar clusters mainly to detect young transiting planets (and to study other variability phenomena on time-scales from minutes to years). The telescope network enables us to observe the targets continuously for several days in order not to miss any transit. We aim to constrain planet formation models and their time-scales by discovering planets younger than ∼100 Myr and determining not only their orbital parameters, but also measuring their true masses and radii, which is possible so far only by the transit method. Here, we present an overview and first results.
Links:
http://onlinelibrary.wiley.com/doi/10.1002/asna.201111573/pdf