# Tudor Stanescu

Condensed Matter Theory

### Education

### Research

Dr. Stanescu is a theoretical condensed matter physicist whose research interests are driven by current experimental observations that challenge the standard paradigms of transport, magnetism, or superconductivity and by those aimed at creating and probing novel, unconventional phases and quantum states. Materials characterized by strong correlations, systems with spin-orbit interactions, or those characterized by strong orbital effects are some of the likely candidates.

*"Many of these materials have a huge potential for applications and are actively studied with the goal of developing new functionalities and improved capabilities in areas ranging from the design and construction of electronic devices, to ultra-sensitive quantum interferometry and fault-tolerant topological quantum computing. Understanding the properties of these materials pose serious theoretical challenges."*

A major task in the area of spin electronics (spintronics) is understanding spin dynamics in semiconducting systems with spin-orbit interaction. Spintronics with semiconductors is very attractive, as it combines the potential of semiconductors (control of current by gates, coupling with optics, etc) with the potential of magnetic materials (control of current by spin manipulation, non-volatility, etc). In these materials, the coupling of the orbital motion of electrons to an internal degree of freedom (the spin) leads to interesting phenomena, such as the spin Hall effect. Dr. Stanescu’s research focuses on studying the effects of disorder, finite temperature and interactions on the dynamics of spin-orbit coupled electrons.

Topological insulators are systems that transcend the standard way of classifying condensed matter quantum states according to the symmetries that they break. They posses a more subtle organizational structure (sometimes called topological order), which is responsible for the remarkable robustness of some of their properties (such as, for example, the quantized Hall conductance). Several materials that are quasi two-dimensional or three dimensional topological insulators were recently discovered experimentally. They are characterized by the existence of gapless edge/surface states that are robust against disorder and interactions and have a non-trivial spin structure. Dr. Stanescu’s research focuses on studying the unconventional transport properties of these surface states in thin films and at interfaces between topological insulators and magnetic or superconducting systems.

Understanding the physics of strongly correlated electron systems is one of the most fascinating and difficult problems in condensed matter physics. The pseudo-gap phenomenon found in the underdoped high-temperature superconducting cuprates constitutes a remarkable example. As the Mott insulating phase is approached, the independent quasi-particle picture that sits at the heart of Landau’s Fermi liquid theory breaks down and, consequently, a different framework for describing the underlying physics is required. Powerful numerical methods, such as the cluster extensions of Dynamical Mean Field Theory (DMFT), offer valuable insight into this Mott-type physics governed by spectral weight transfer over wide energy scales (Mottness). Dr. Stanescu’s research aims at optimizing and generalizing these numerical methods and using them to unveil the relevant correlations that control the physics in the strongly correlated regime.

### Publications

- B. Anderson, T.D. Stanescu and V. Galitski, ``Bulk Spin-Hall Effect,’’ arXiv: 0905.2771 (2009).

- T.D. Stanescu, V. Galitski, J.Y. Vaishnav, C.W. Clark and S. Das Sarma, ``Topological Insulators and Metals in Atomic Optical Lattices,’’ Phys. Rev. A 79, 053639 (2009).

- D. Galanakis, T.D. Stanescu and P. Phillips, ``Mott transition on a triangular lattice,’’ Phys. Rev. B 79, 115116 (2009).

- T.D. Stanescu, V. Galitski and H.D. Drew, ``Effective masses in a strongly anisotropic Fermi liquid,’’ Phys. Rev. Lett. 101, 066405 (2008).

- T.D. Stanescu, V. Galitski and S. Das Sarma, ``Orbital fluctuation mechanism for superconductivity in iron-based compounds,’’ Phys. Rev. B 78, 195114 (2008).

- T.D. Stanescu, B. Anderson and V. Galitski, ``Spin-orbit coupled Bose-Einstein condensates,’’ Phys. Rev. A 78, 023616 (2008).

- M. Civelli, M. Capone, A. Georges, K. Haule, O. Parcollet, T. D. Stanescu and G. Kotliar, ``Nodal/Antinodal Dichotomy and the Two Gaps of a Superconducting Doped Mott Insulator,’’ Rev. Lett. 100, 046402 (2008).

- T.D. Stanescu, C. Zhang and V. Galitski, ``Non-equilibrium spin dynamics in a trapped Fermi gas with effective spin-orbit interaction,’’ Phys. Rev. Lett. 99, 110403 (2007).

- T.D. Stanescu and V. Galitski, ``Spin relaxation in a generic two-dimensional spin-orbit coupled system,’’ Phys. Rev. B 75, 125307 (2007).

- T.D. Stanescu, P. W. Phillips, and T.-P. Choy, ``Theory of the Luttinger surface in doped Mott insulators,’’ Phys. Rev. B 75, 104503 (2007).

- T.D. Stanescu and V. Galitski, ``Surface states, Friedel oscillations, and spin accumulation in p-doped semiconductors,’’ Phys. Rev. B 74, 205331 (2006).

- T.D. Stanescu, M. Civelli, K. Haule, and G. Kotliar, ``A Cellular Dynamical Mean Field Theory Approach to Mottness,’’ Annals of Physics 321, 1682 (2006).

- T.D. Stanescu and G. Kotliar, ``Fermi arcs and hidden zeros of the Green function in the pseudogap state,’’ Phys. Rev. B 74, 125110 (2006).

- P. Phillips, D. Galanakis, and T.D. Stanescu, ``Absence of asymptotic freedom in doped Mott insulators: Breakdown of strong coupling expansions,’’ Phys. Rev. Lett. 93, 267004 (2004)

- T.D. Stanescu, G. Kotliar, ``Strong Coupling Theory for Interacting Lattice Models,’’ Phys. Rev. B 70, 205112 (2004).

- T.D. Stanescu, P. Phillips, ``Nonperturbative approach to full Mott behavior,’’ Phys. Rev. B 69, 245104 (2004).

- T.D. Stanescu, P. Phillips, ``Pseudogap in Doped Mott Insulators is the Near-neighbour Analogue of the Mott Gap,’’ Phys. Rev. Lett. 91, 017002 (2003).

- T.D. Stanescu, P. Phillips, ``Nearest-neighbor attraction stabilizes staggered currents in the two-dimensional Hubbard model,’’ Phys. Rev. B 64, 220509 (2001).

- T.D. Stanescu, P. Phillips, ``Local dynamics and strong correlation physics: One- and two-dimensional half-filled Hubbard models,’’ Phys. Rev. B 64, 235117 (2001).

- T.D. Stanescu, I. Martin, P. Phillips, ``d_{x2-y2} pairing of composite excitations in the two-dimensional Hubbard model,’’ Phys. Rev. B 62, 4300 (2000).

- T.D. Stanescu, I. Martin, P. Phillips, ``Finite-temperature density instability at high Landau level occupancy,’’ Phys. Rev. Lett., 84, 1288 (2000).

- A. Manolescu, T. Stanescu, ``Homogeneous-inhomogeneous transitions in a Landau level with spin splitting,’’ Z. Phys. B 94, 87-90 (1994).