arXiv subjects

Yi-Sheng Chai

Publications and source records attributed to Yi-Sheng Chai.

5 recordsLinked to original sources

arXiv2024

Resonant Quantum Magnetodielectric Effect in Multiferroic Metal-Organic Framework [CH3NH3]Co(HCOO)3

We report the observation of both resonant quantum tunneling of magnetization (RQTM) and resonant quantum magnetodielectric (RQMD) effect in the perovskite multiferroic metal-organic framework [CH3NH3]Co(HCOO)3. An intrinsic magnetic phase separation emerges at low temperatures due to hydrogen-bond-modified long range super-exchange interaction, leading to the coexistence of canted antiferromagnetic order and single-ion magnet. Subsequently, a stair-shaped magnetic hysteresis loop along the [101] direction characterizing the RQTM appears below the magnetic blocking temperature. More interestingly, the magnetic field dependence of dielectric permittivity exhibits pronounced negative peaks at the critical fields corresponding to the RQTM, a phenomenon termed the RQMD effect which enables electrical detection of the RQTM. These intriguing properties make the multiferroic metal-organic framework a promising candidate for solid-state quantum computing.

cond-mat.mtrl-sci↗

arXiv2021

Giant magnetostriction and nonsaturating electric polarization up to 60 T in the polar magnet CaBaCo4O7

Giant magnetostriction in insulating magnetic materials is highly required for applications but is rarely observed. Here we show that giant magnetostriction (> 1500 ppm) can be achieved in an insulating transition metal oxide CaBaCo4O7 where the ferrimagnetic ordering at TC ~ 62 K is associated with a huge change in the lattice. Moreover, because this material is pyroelectric with a non-switchable electric polarization (P), the giant magnetostriction results in a record-breaking magnetoelectric effect - a gigantic change of electric polarization (deltaP ~ 1.6 μC/cm2) in response to the applied magnetic field up to 60 T. Geometric frustration as well as the orbital instability of Co2+/Co3+ ions is believed to play a crucial role in the giant magnetostriction. Our study provides new insights on how to achieve both giant magnetostriction and pronounced magnetoelectric effect in insulating transition metal oxides.

cond-mat.str-el↗

arXiv2018

Measurement of the angle dependence of magnetostriction in pulsed magnetic fields using a piezoelectric strain gauge

We present a high resolution method for measuring magnetostriction in millisecond pulsed magnetic fields at cryogenic temperatures with a sensitivity of $1.11\times10^{-11}/\sqrt{\rm Hz}$. The sample is bonded to a thin piezoelectric plate, such that when the sample's length changes, it strains the piezoelectric and induces a voltage change. This method is more sensitive than a fiber-Bragg grating method. It measures two axes simultaneously instead of one. The gauge is small and versatile, functioning in DC and millisecond pulsed magnetic fields. We demonstrate its use by measuring the magnetostriction of Ca$_3$Co$_{1.03}$Mn$_{0.97}$O$_6$ single crystals in pulsed magnetic fields. By comparing our data to new and previously published results from a fiber-Bragg grating magnetostriction setup, we confirm that this method detects magnetostriction effects. We also demonstrate the small size and versatility of this technique by measuring angle dependence with respect to the applied magnetic field in a rotator probe in 65 T millisecond pulsed magnetic fields.

cond-mat.mtrl-sci↗

arXiv2015

Quantum electric-dipole liquid on a triangular lattice

Geometric frustrations and quantum mechanical fluctuations may prohibit the formation of long-range ordering even at the lowest temperature, and therefore liquid-like ground states could be expected. A good example is the quantum spin liquid in frustrated magnets that represents an exotic phase of matter and is attracting enormous interests. Geometric frustrations and quantum fluctuations can happen beyond magnetic systems. Here we propose that quantum electric-dipole liquids, analogs to quantum spin liquids, could emerge in frustrated dielectrics where antiferroelectrically coupled small electric dipoles reside on a triangular lattice. The quantum paraelectric hexaferrite BaFe12O19, in which small electric dipoles originated from the off-center displacement of Fe3+ in the FeO5 bipyramids constitute a two-dimensional triangular lattice, represents a promising candidate to generate the anticipated electric-dipole liquid. We present a series of experimental evidences, including dielectric permittivity, heat capacity, and thermal conductivity measured down to 66 mK, to reveal the existence of a nontrivial ground state in BaFe12O19, characterized by itinerant low-energy excitations with a small gap, to which we interpret as an exotic liquid-like quantum phase. The quantum electric-dipole liquids in frustrated dielectrics open up a fresh playground for fundamental physics and may find applications in quantum information and computation as well.

cond-mat.str-el↗

arXiv2014

Non-d$^0$ Electric Dipole in FeO$_5$ bipyramid: a New Resource for Quantum Paraelectrics, Ferroelectrics and Multiferroics

Electric polarization in conventional ferroelectric oxides usually involves nonmagnetic transition-metal ions with an empty d shell (the d$^0$ rule). Here we unravel a new mechanism for local electric dipoles based on magnetic Fe$^{3+}$ (3d$^5$) ion violating the d$^0$ rule. The competition between the long-range Coulomb interaction and short-range Pauli repulsion in a FeO$_5$ bipyramid with proper lattice parameters would favor an off-center displacement of Fe$^{3+}$ that induces a local electric dipole. The manipulation of this kind of non-d$^0$ electric dipoles opens up a new route for generating unconventional dielectrics, ferroelectrics, and multiferroics. As a prototype example, we show that the non-d$^0$ electric dipoles in ferrimagnetic hexaferrites (Ba,Sr)Fe$_{12}$O$_{19}$ lead to a new family of magnetic quantum paraelectrics.

cond-mat.str-el↗