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Theory of the Competition Between Spin Density Waves and D-Wave Superconductivity in the Underdoped Cuprates

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Theory of the Competition Between Spin Density Waves and D-Wave Superconductivity in the Underdoped Cuprates Theory of the competition between spin density waves and d-wave superconductivity in the underdoped cuprates Talk online: sachdev.physics.harvard.edu HARVARD Where is the quantum critical point in the cuprate superconductors ? arXiv:0907.0008 Talk online: sachdev.physics.harvard.edu HARVARD Hole dynamics in an antiferromagnet across a deconfined quantum critical point, R. K. Kaul, A. Kolezhuk, M. Levin, S. Sachdev, and T. Senthil, Phys. Rev. B 75, 235122 (2007). Algebraic charge liquids R. K. Kaul, Yong-Baek Kim, S. Sachdev, and T. Senthil, Nature Physics 4, 28 (2008). Destruction of Neel order in the cuprates by electron doping, R. K. Kaul, M. Metlitksi, S. Sachdev, and Cenke Xu, Physical Review B 78, 045110 (2008). Paired electron pockets in the underdoped cuprates, V. Galitski and S. Sachdev, Physical Review B 79, 134512 (2009). Competition between spin density wave order and superconductivity in the underdoped cuprates, Eun Gook Moon and S. Sachdev, Physical Review B 80, 035117 (2009). Fluctuating spin density waves in metals S. Sachdev, M. Metlitski, Yang Qi, and Cenke Xu arXiv:0907.3732 HARVARD The cuprate superconductors Crossovers in transport properties of hole-doped cuprates * ? coh (K) ( ) 2 S-shaped + or upturns (1 < < 2) ? FL A in ( ) F 2 M -wave SC 0 0.05 0.1 0.15 0.2 0.25 0.3 Hole doping N. E. Hussey, J. Phys: Condens. Matter 20, 123201 (2008) Canonical quantum critical phase diagram of coupled-dimer antiferromagnet Quantum critical S. Sachdev and Classical Dilute J. Ye, Phys. Rev. Lett. spin triplon 69, 2411 (1992). waves gas Neel order Pressure in TlCuCl3 Christian Ruegg et al. , Phys. Rev. Lett. 100, 205701 (2008) Crossovers in transport properties of hole-doped cuprates Strange metal S. Sachdev and J. Ye, Phys. Rev. Lett. (K) 69, 2411 (1992). T C. M. Varma, Phys. Rev. Lett. 83, 3538 (1999). A xm F d M -wave SC 0 0.05 0.1 0.15 0.2 0.25 0.3 Hole doping x Strange metal: quantum criticality of optimal doping critical point at x = xm ? Only candidate quantum critical point observed at low T Strange metal (K) T xs A F d M -wave SC 0 0.05 0.1 0.15 0.2 0.25 0.3 Hole doping x Spin density wave order present below a quantum critical point at x = xs with x 0.12 in the La series of cuprates s ≈ Γ Γ Theory of quantum criticality in the cuprates Strange R. Daou et al., Metal Fluctuating Nature Physics Fermi Large 5, 31 - 34 pockets Fermi (2009) surface Spin density wave (SDW) Underlying SDW ordering quantum critical point in metal at x = xm Fermi surfaces in electron- and hole-doped cuprates Hole states occupied Γ Electron states occupied Γ Effective Hamiltonian for quasiparticles: H = t c† c ε c† c 0 − ij iα iα ≡ k kα kα i<j ! !k with tij non-zero for first, second and third neighbor, leads to satisfactory agree- ment with experiments. The area of the occupied electron states, e, from Luttinger’s theory is A 2π2(1 p) for hole-doping p e = − A 2π2(1 + x) for electron-doping x " The area of the occupied hole states, h, which form a closed Fermi surface and so appear in quantum oscillation experimentsA is =4π2 . Ah − Ae Spin density wave theory A spin density wave (SDW) is the spontaneous appearance of an oscillatory spin polarization. The electron spin polar- ization is written as iK r S!(r, τ)=!ϕ (r, τ)e · where !ϕ is the SDW order parameter, and K is a fixed or- dering wavevector. For simplicity we will consider the case of K =(π, π), but our treatment applies to general K. Spin density wave theory In the presence of spin density wave order, !ϕ at wavevector K = (π, π), we have an additional term which mixes electron states with momentum separated by K H = !ϕ c† !σ c sdw · k,α αβ k+K,β k!,α,β where !σ are the Pauli matrices. The electron dispersions obtained by diagonalizing H + H for !ϕ (0, 0, 1) are 0 sdw ∝ εk + εk+K εk εk+K 2 Ek = − + ϕ ± 2 ± 2 "# $ This leads to the Fermi surfaces shown in the following slides for electron and hole doping. Spin density wave theory in hole-doped cuprates Increasing SDW order Γ S. Sachdev, A. V. Chubukov, and A. Sokol, Phys. Rev. B 51, 14874 (1995). A. V. Chubukov and D. K. Morr, Physics Reports 288, 355 (1997). Spin density wave theory in hole-doped cuprates Increasing SDW order Γ Γ S. Sachdev, A. V. Chubukov, and A. Sokol, Phys. Rev. B 51, 14874 (1995). A. V. Chubukov and D. K. Morr, Physics Reports 288, 355 (1997). Spin density wave theory in hole-doped cuprates Increasing SDW order Electron pockets Γ Γ Γ Hole pockets S. Sachdev, A. V. Chubukov, and A. Sokol, Phys. Rev. B 51, 14874 (1995). A. V. Chubukov and D. K. Morr, Physics Reports 288, 355 (1997). Spin density wave theory in hole-doped cuprates Increasing SDW order Γ Γ Γ Γ Hole pockets SDW order parameter is a vector, !ϕ , whose amplitude vanishes at the transition to the Fermi liquid. S. Sachdev, A. V. Chubukov, and A. Sokol, Phys. Rev. B 51, 14874 (1995). A. V. Chubukov and D. K. Morr, Physics Reports 288, 355 (1997). Spin density wave theory in hole-doped cuprates Γ Γ Incommensurate order in YBa2Cu3O6+x A. J. Millis and M. R. Norman, Physical Review B 76, 220503 (2007). N. Harrison, Physical Review Letters 102, 206405 (2009). Evidence for connection between linear resistivity and stripe-ordering in a cuprate with a low Tc Magnetic field of upto 35 T used to suppress superconductivity Linear temperature dependence of resistivity and change in the Fermi surface at the pseudogap critical point of a high-Tc superconductor R. Daou, Nicolas Doiron-Leyraud, David LeBoeuf, S. Y. Li, Francis Laliberté, Olivier Cyr-Choinière, Y. J. Jo, L. Balicas, J.-Q. Yan, J.-S. Zhou, J. B. Goodenough & Louis Taillefer, Nature Physics 5, 31 - 34 (2009) Theory of quantum criticality in the cuprates Strange R. Daou et al., Metal Fluctuating Nature Physics Fermi Large 5, 31 - 34 pockets Fermi (2009) surface Spin density wave (SDW) Underlying SDW ordering quantum critical point in metal at x = xm Theory of quantum criticality in the cuprates Strange Fluctuating,Small Fermi Metal pairedpockets Fermi with Large pairingpockets fluctuations Fermi surface d-wave superconductor Spin density wave (SDW) Onset of d-wave superconductivity hides the critical point x = xm Theory of quantum criticality in the cuprates Strange Fluctuating,Small Fermi Metal pairedpockets Fermi with Large pairingpockets fluctuations Fermi surface d-wave superconductor Spin density wave (SDW) Competition between SDW order and superconductivity moves the actual quantum critical point to x = xs <xm. Theory of quantum criticality in the cuprates Strange Fluctuating,Small Fermi Metal pairedpockets Fermi with Large pairingpockets fluctuations Fermi surface d-wave superconductor Spin density wave (SDW) Competition between SDW order and superconductivity moves the actual quantum critical point to x = xs <xm. Theory of quantum criticality in the cuprates Strange Fluctuating,Small Fermi Metal pairedpockets Fermi with Large pairingpockets fluctuations Fermi surface d-wave Magnetic quantum superconductor Thermally criticality fluctuating SDW Spin gap Spin density wave (SDW) Competition between SDW order and superconductivity moves the actual quantum critical point to x = xs <xm. Outline 1. Phenomenological quantum theory of competition between superconductivity and SDW order Survey of recent experiments 2. Superconductivity in the overdoped regime BCS pairing by spin fluctuation exchange 3. Superconductivity in the underdoped regime U(1) gauge theory of fluctuating SDW order Outline 1. Phenomenological quantum theory of competition between superconductivity and SDW order Survey of recent experiments 2. Superconductivity in the overdoped regime BCS pairing by spin fluctuation exchange 3. Superconductivity in the underdoped regime U(1) gauge theory of fluctuating SDW order Phenomenological quantum theory of competition between superconductivity (SC) and spin-density wave (SDW) order Write down a Landau-Ginzburg action for the quantum fluctua- tions of the SDW order (!ϕ ) and superconductivity (ψ): 2 1 c r u 2 = d2rdτ (∂ !ϕ )2 + ( !ϕ )2 + !ϕ 2 + !ϕ 2 S 2 τ 2 ∇x 2 4 ! " # $ + κ !ϕ2 ψ 2 | | % 4 2 2 2 ψ + d r ( x i(2e/!c) )ψ ψ + | | | ∇ − A | − | | 2 ! " % where κ > 0 is the repulsion between the two order parameters, and = H is the applied magnetic field. ∇×A E. Demler, S. Sachdev and Y. Zhang, Phys. Rev. Lett. 87, 067202 (2001). See also E. Demler, W. Hanke, and S.-C. Zhang, Rev. Mod. Phys. 76, 909 (2004); S. A. Kivelson, D.-H. Lee, E. Fradkin, and V. Oganesyan, Phys. Rev. B 66, 144516 (2002). Phenomenological quantum theory of competition between superconductivity (SC) and spin-density wave (SDW) order Write down a Landau-Ginzburg action for the quantum fluctua- tions of the SDW order (!ϕ ) and superconductivity (ψ): 2 1 c r u 2 = d2rdτ (∂ !ϕ )2 + ( !ϕ )2 + !ϕ 2 + !ϕ 2 S 2 τ 2 ∇x 2 4 ! " # $ + κ !ϕ2 ψ 2 | | % 4 2 2 2 ψ + d r ( x i(2e/!c) )ψ ψ + | | | ∇ − A | − | | 2 ! " % where κ > 0 is the repulsion between the two order parameters, and = H is the applied magnetic field. ∇×A E. Demler, S. Sachdev and Y. Zhang, Phys. Rev. Lett. 87, 067202 (2001). See also E. Demler, W. Hanke, and S.-C. Zhang, Rev. Mod. Phys. 76, 909 (2004); S. A. Kivelson, D.-H. Lee, E. Fradkin, and V. Oganesyan, Phys. Rev. B 66, 144516 (2002). Phenomenological quantum theory of competition between superconductivity (SC) and spin-density wave (SDW) order Write down a Landau-Ginzburg action for the quantum fluctua- tions of the SDW order (!ϕ ) and superconductivity (ψ): 2 1 c r u 2 = d2rdτ (∂ !ϕ )2 + ( !ϕ )2 + !ϕ 2 + !ϕ 2 S 2 τ 2 ∇x 2 4 ! " # $ + κ !ϕ2 ψ 2 | | % 4 2 2 2 ψ + d r ( x i(2e/!c) )ψ ψ + | | | ∇ − A | − | | 2 ! " % where κ > 0 is the repulsion between the two order parameters, and = H is the applied magnetic field.
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