Hopkinson, John M., Kee, Hae-Young
We study a classical ferromagnetic Heisenberg model in the presence of Dzyaloshinskii-Moriya interactions on the corner-shared triangle lattice formed by the Mn sites of MnSi. We show that the...
Puetter, Christoph M., Lawler, Michael J., Kee, Hae-Young
We present a theory of the anisotropy tuned quantum phase transition between spin nematic and spin-Peierls phases in S=1 systems with significant bi-quadratic exchange interactions. Based on quantum...
Quantum oscillations of ortho-II YBa_2Cu_3O_6.5 (2008)
Podolsky, Daniel, Kee, Hae-Young
Motivated by quantum oscillations observed in highly ordered ortho-II YBa_2Cu_3O_6.5, we study the Fermi surface topology of a d-density wave (ddw) state in the presence of the ortho-II potential. We...
Fate of partial order on the trillium and distorted windmill lattices (2008)
Isakov, Sergei V., Hopkinson, John M., Kee, Hae-Young
The classical Heisenberg model on the trillium and distorted windmill lattices exhibits a degenerate ground state within large-$N$ theory, where the degenerate wavevectors form a surface and line, in...
Half quantum vortices and Majorana fermions in triplet superconductors (2007)
Kee, Hae-Young, Raghavan, Aditya, Maki, Kazumi
Half quantum vortices (HQVs) in superfluid $^3He-A$ have been speculated since 1976. Two years ago, Yamashita et al reported a very unusual NMR satellite in the rotating superfluid $^3He-A$ in a...
Chakravarty, Sudip, Kee, Hae-Young
Recent quantum oscillation measurements in high temperature superconductors in high magnetic fields and low temperatures have ushered in a new era. These experiments explore the normal state from...
Kee, Hae-Young, Doh, Hyeonjin, Grzesiak, Thomas
This paper consists of two important theoretical observations on the interplay between l = 2 condensates; d-density wave (ddw), electronic nematic and d-wave superconducting states. (1) There is...
Meta-nematic transitions in a bilayer system: Application to the bilayer ruthenate (2007)
Puetter, Christoph, Doh, Hyeonjin, Kee, Hae-Young
It was suggested that the two consecutive metamagnetic transitions and the large residual resistivity discovered in Sr$_3$Ru$_2$O$_7$ can be understood via the nematic order and its domains in a...
Topological spin liquid on the hyper-kagome lattice of Na_4Ir_3O_8 (2007)
Lawler, Michael J., Kee, Hae-Young, Kim, Yong Baek, Vishwanath, Ashvin
Recent experiments on the "hyper-kagome" lattice system Na$_4$Ir$_3$O$_8$ have demonstrated that it is a rare example of a three dimensional spin-1/2 frustrated antiferromagnet. We investigate the...
An electronic nematic state spontaneously breaks a point-group symmetry of an underlying lattice. As a result, the nematic-isotropic transition accompanies a Fermi surface distortion. However, the...
Half quantum vortex in superfluid $^3$He-A phase in parallel plate geometry (2007)
The half quantum vortex(HQV) in condensate has been studied, since it was predicted by Salomaa and Volovik in superfluid $^3$He-A phase. However, an experimental evidence for its existence has not...
Theory of non-Fermi liquid near a diagonal electronic nematic state on a square lattice (2007)
We study effects of Fermi surface fluctuations on a single-particle life time near the diagonal electronic nematic phase on a two-dimensional square lattice. It has been shown that there exists a...
Classical antiferromagnet on a hyperkagome lattice (2006)
Hopkinson, John M., Isakov, Sergei V., Kee, Hae-Young, Kim, Yong Baek
Motivated by recent experiments on Na_4Ir_3O_8 [Y. Okamoto, M. Nohara, H. Aruga-Katori, and H. Takagi, arXiv:0705.2821 (unpublished)], we study the classical antiferromagnet on a frustrated...
A microscopic model for spiral ordering along (110) on the MnSi lattice (2006)
Hopkinson, John M., Kee, Hae-Young
We study an extended Heisenberg model on the MnSi lattice. In the cubic B20 crystal structure of MnSi, Mn atoms form lattices of of corner-shared equilateral triangles. We find an ubiquitous spiral...
A novel route to a finite center-of-mass momentum pairing state; current driven FFLO state (2006)
Doh, Hyeonjin, Song, Matthew, Kee, Hae-Young
The previously studied Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state is stabilized by a magnetic field via the Zeeman coupling in spin-singlet superconductors. Here we suggest a novel route to...
Interplay between parallel and diagonal electronic nematic phases in interacting systems (2006)
Doh, Hyeonjin, Friedman, Nir, Kee, Hae-Young
An electronic nematic phase can be classified by a spontaneously broken discrete rotational symmetry of a host lattice. In a square lattice, there are two distinct nematic phases. The parallel...
Geometric frustration inherent to the trillium lattice, a sublattice of the B20 structure (2005)
Hopkinson, John M., Kee, Hae-Young
We study the classical Heisenberg model on a recently identified three dimensional corner-shared equilateral triangular lattice, a magnetic sublattice to a large class of systems with the symmetry...
We study spin and charge susceptibilities in the d-wave superconducting state whose underlying electronic dispersion is anisotropic due to the formation of the electronic nematic order. We show that...
Itinerant metamagnetism induced by electronic nematic order (2004)
Kee, Hae-Young, Kim, Yong Baek
It is shown that metamagnetic transition in metals can occur via the formation of electronic nematic order. We consider a simple model where the spin-dependent Fermi surface instability gives rise to...
Supercurrent in Nodal Superconductors (2004)
Khavkine, Igor, Kee, Hae-Young, Maki, Kazumi
In recent years, a number of nodal superconductors have been identified; d-wave superconductors in high T_c cuprates, CeCoIn$_5$, and \kappa-(ET)_2Cu(NCS)_2, 2D f-wave superconductor in Sr_2RuO_4 and...
Formation of Electronic Nematic Phase in Interacting Systems (2004)
Khavkine, Igor, Chung, Chung-Hou, Oganesyan, Vadim, Kee, Hae-Young
We study the formation of an electronic nematic phase characterized by a broken point-group symmetry in interacting fermion systems within the weak coupling theory. As a function of interaction...
Chakravarty, Sudip, Kee, Hae-Young, Voelker, Klaus
A remarkable mystery of the copper oxide high-transition-temperature (Tc) superconductors is the dependence of Tc on the number of CuO2 layers, n, in the unit cell of a crystal. In a given family of...
Critical Current of the Spin-Triplet Superconducting Phase in Sr$_2$RuO$_4$ (2003)
Kee, Hae-Young, Kim, Yong Baek, Maki, K.
There have been two different proposals for the spin-triplet order parameter of the superconducting phase in Sr$_2$RuO$_4$; an $f$-wave order parameter and the multigap model where some of the bands...
Robustness of d-Density Wave Order to Nonmagnetic Impurities (2003)
Effect of finite density of nonmagnetic impurities on a coexisting phase of d-density wave (DDW) order and d-wave superconducting (DSC) order is studied using Bogoliubov-de Gennes (BdG) method. The...
Signatures of Electronic Nematic Phase at Isotropic-Nematic Phase Transition (2003)
Kee, Hae-Young, Kim, Eugene H., Chung, Chung-Hou
The electronic nematic phase occurs when the point-group symmetry of the lattice structure is broken, due to electron-electron interactions. We study a model for the nematic phase on a square lattice...
Raman Spectra of Triplet Superconductor in Sr$_2$RuO$_4$ (2002)
Kee, Hae-Young, Maki, K., Chung, C. H.
We study the Raman spectra of spin-triplet superconductors in Sr$_2$RuO$_4$. The p-wave and f-wave symmetries are considered. We show that there is the clapping mode with frequency of $\sqrt{2}...
Condensation energy and the mechanism of superconductivity (2002)
Chakravarty, Sudip, Kee, Hae-Young, Abrahams, Elihu
Condensation energy in a superconductor cannot be precisely defined if mean-field theory fails to hold. This implies that in the case of high temperature superconductors, discussions of quantitative...
Effect of Ring Exchange on Orbital Antiferromagnet (2002)
Chung, C. H., Kee, Hae-Young, Kim, Yong Baek
We study the effect of four-particle ring exchange process on orbital antiferromagnetic state that occurs in some correlated electron systems in two dimensions. The primary question is whether the...
Sound Propagation in Nematic Fermi Liquid (2002)
We study the longitudinal sound propagation in the electronic nematic Fermi liquid where the Fermi surface is distorted due to the spontaneously broken rotational symmetry. The behavior of the sound...
Pairing Instability in a Nematic Fermi Liquid (2002)
Kim, Yong Baek, Kee, Hae-Young
Nematic Fermi liquid arises when the system of interacting fermions spontaneously breaks the rotational symmetry while the translational symmetry is preserved. We consider a Nematic Fermi liquid of...
"Quasiparticle Charge" in Superconductors: Effect of Mott Physics or Hidden Order Parameter ? (2002)
Kee, Hae-Young, Kim, Yong Baek
The renormalization factor, dubbed ``quasiparticle charge'' Z_e, of the coupling between the supercurrent and quasiparticles was analyzed in the context of high temperature cuprates in a recent paper...
Orbital Magnetism in the Cuprates (2001)
Chakravarty, Sudip, Kee, Hae-Young, Nayak, Chetan
The pseudogap phase of the cuprate superconductors is argued to be characterized by a hidden broken symmetry of d-wave character in the particle-hole channel that leads to staggered orbital...
Kee, Hae-Young, Kim, Yong Baek
We study the effect of finite chemical potential on the d-density wave state that has been proposed to explain the pseudogap phenomena in underdoped cuprates. We find that the specific heat anomaly...
What the resonance peak cannot do (2001)
Kee, Hae-Young, Kivelson, Steven A., Aeppli, G.
In certain cuprates, a spin 1 resonance mode is prominent in the magnetic structure measured by neutron scattering. It has been proposed that this mode is responsible for significant features seen in...
Demler, Eugene, Nayak, Chetan, Kee, Hae-Young, Kim, Yong Baek, Senthil, T.
We discuss possible patterns of electron fractionalization in strongly interacting electron systems. A popular possibility is one in which the charge of the electron has been liberated from its Fermi...
Neutron Scattering Signature of d-density Wave Order in the Cuprates (2001)
Chakravarty, Sudip, Kee, Hae-Young, Nayak, Chetan
An ordered $d$-density wave (DDW) state has been proposed as an explanation of the pseudogap phase in underdoped high-temperature superconductors. The staggered currents associated with this order...
Spin and Current Correlation Functions in the \bf d-density Wave State of the Cuprates (2001)
Tewari, Sumanta, Kee, Hae-Young, Nayak, Chetan, Chakravarty, Sudip
We calculate the spin-spin and current-current correlation functions in states exhibiting d_{{x^2}-{y^2}}-density wave (DDW) order, d_{{x^2}-{y^2}} superconducting order (DSC), or both types of...
Effect of Doping-induced Disorder on Transition Temperature in High $T_c$ Cuprates (2000)
We study the effect of disorder induced by doping on the transition temperature in high $T_c$ cuprates. Since the impurity lies between the CuO$_2$ planes, the momentum transfer is restricted by...
Half-quantum vortex and d-soliton in Sr$_2$RuO$_4$ (2000)
Kee, Hae-Young, Kim, Yong Baek, Maki, Kazumi
Assuming that the superconductivity in Sr$_2$RuO$_4$ is described by a planar p-wave order parameter, we consider possible topological defects in Sr$_2$RuO$_4$. In particular, it is shown that both...
Collective modes and sound propagation in a p-wave superconductor: Sr$_2$RuO$_4$ (1999)
Kee, Hae-Young, Kim, Yong Baek, Maki, Kazumi
There are five distinct collective modes in the recently discovered p-wave superconductor Sr$_2$RuO$_4$; phase and amplitude modes of the order parameter, clapping mode (real and imaginary), and spin...
Probing Pairing Symmetry in Sr$_2$RuO$_4$ (1999)
We study the spin dynamics in a p-wave superconductor at the nesting vector associated with $\alpha$ and $\beta$ bands in Sr$_2$RuO$_4$. We find a collective mode at the nesting vector in the...
On Measuring Condensate Fraction in Superconductors (1999)
Chakravarty, Sudip, Kee, Hae-Young
An analysis of off-diagonal long-range order in superconductors shows that the spin-spin correlation function is significantly influenced by the order if the order parameter is anisotropic on a...
Spin waves in a two dimensional p-wave superconductor: Sr$_2$RuO$_4$ (1999)
Kee, Hae-Young, Kim, Yong Baek, Maki, Kazumi
We study spin excitations in a two dimensional p-wave superconductor with ${\vec \Delta} = {\hat d}({\hat k}_1 \pm i {\hat k}_2)$ symmetry in the context of the newly discovered superconducting...
Frustrated kinetic energy, the optical sum rule, and the mechanism of superconductivity (1998)
Chakravarty, Sudip, Kee, Hae-Young, Abrahams, Elihu
The theory that the change of the electronic kinetic energy in a direction perpendicular to the CuO-planes in high-temperature superconductors is a substantial fraction of the condensation energy is...
Incommensurate Charge and Spin Fluctuations in d-wave Superconductors (1998)
Kee, Hae-Young, Kim, Yong Baek
We show analytic results for the irreducible charge and spin susceptibilities, $\chi_0 (\omega, {\bf Q})$, where ${\bf Q}$ is the momentum transfer between the nodes in d-wave superconductors. Using...
Polarizability and single particle spectra of two-dimensional s- and d-wave superconductors (1998)
We present analytic results for the polarizabilities, $\chi({\bf Q},\omega)$, in the charge, spin, and current channels for two-dimensional s- and d-wave superconductors for large momentum transfer....
Theory of Tunneling Anomaly in Superconductor above Paramagnetic Limit (1998)
Kee, Hae-Young, Aleiner, I. L., Altshuler, B. L.
We study the tunneling density of states (DoS) in the superconducting systems driven by Zeeman splitting $E_Z$ into the paramagnetic phase. We show that, even though the BCS gap disappears,...
Conductance fluctuations at the fractional quantum Hall plateau transitions (1997)
Kee, Hae-Young, Kim, Yong Baek, Abrahams, Elihu, Bhatt, R. N.
We obtain a ``mean field'' scaling flow of the longitudinal and the Hall conductivities in the fractional quantum Hall regime. Using the composite fermion picture and assuming that the composite...
Phonon Anomalies Induced by Superconductivity (1996)
We calculate the electronic polarizability in the superconducting state near extremum vectors ${\vec Q}_0$ of the Fermi surface. A pole appears in the polarizability at frequencies $\omega$ near the...
Temperature and Pressure Effects on the Resistivity of the Manganese Oxides (1996)
The temperature and pressure effects on the resistivity of the manganese oxides are studied analytically via the Kondo lattice model with a strong Hund's coupling. We obtain analytically the...
Strong correlation effects in the doped Hubbard model in infinite dimensions (1995)
The density of states and the optical conductivity of the doped Hubbard model on a Bethe lattice with infinite connectivities have been studied using an analytic variant of the Lanczos continued...
Quantitative Description of $V_2O_3$ by the Hubbard Model in Infinite Dimensions (1995)
We show that the analytic single-particle density of states and the optical conductivity for the half-filled Hubbard model on the Bethe lattice in infinite dimensions describe quantitatively the...
Analytic Treatment of Mott-Hubbard Transition in the Half-Filled Hubbard Model (1995)
The Mott-Hubbard transition in the half-filled Hubbard model is studied analytically for the paramagnetic ground state and the classical N\'{e}el state. The single-particle density of states is...
Multi-Channel Kondo Necklace (1993)
A multi--channel generalization of Doniach's Kondo necklace model is formulated, and its phase diagram studied in the mean--field approximation. Our intention is to introduce the possible simplest...
Underscreened Kondo Necklace (1993)
It has been suggested recently by Gan, Coleman, and Andrei that studying the underscreened Kondo problem may help to understand the nature of magnetism in heavy fermion systems. Motivated by...