FIG 2 - uploaded by Sauri Bhattacharyya

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# Top row: Phonon lineshape for q = (π, π) on a linear (a) and logarithmic (b) scale. The temperatures chosen are-T /TF M = 0.01, 0.5, 1.0, 1.5. We observe a ∼ 15% softening of mode frequency and a sharp increase in the linewidth with T in (a). The accumulation of low-energy weight is emphasized in (b), where the inset shows a detailed T dependence. Middle: the same analysis is repeated for q = (π/2, π/2) in (c) and (d). Similar trends persist with much reduced extent. Bottom: Theoretically extracted 'softening' ∆¯ ω (π,π) (T ) = ¯ ω (π,π) (0) − ¯ ω (π,π) (T ) and thermal broadening ∆Γ (π,π) (T ) = Γ (π,π) (T ) − Γ (π,π) (0) in (e) is compared to corresponding quantities for q = qCE from experiments (f). Qualitative trends are similar.

Source publication

We solve for the finite temperature collective mode dynamics in the Holstein-double exchange problem, using coupled Langevin equations for the phonon and spin variables. We present results in a strongly anharmonic regime, close to a polaronic instability. For our parameter choice the system transits from an `undistorted' ferromagnetic metal at low...

## Contexts in source publication

**Context 1**

... will discuss the relative insensitivity of magnons to phonon physics later. Fig.2 examines phonon lineshapes in detail at two momenta, q = (π, π) and (π/2, π/2). ...

**Context 2**

... the real material, the model we use is two dimensional, involves Holstein rather than cooperative JT phonons, and does not include AF couplings. As Figs.2(e)-(f) demonstrate the phonon softening at the short range ordering wavevector follows similar trends in theory and experiment roughly upto T F M , beyond which they deviate. The fractional softening near T F M however differs by more than a factor of two. ...

**Context 3**

... Fig.2, we show the distribution of displacements (P (x, T )) and electron density P (n, T ) in four temperature regimes. ...

**Context 4**

... will discuss the relative insensitivity of magnons to phonon physics later. Fig.2 examines phonon lineshapes in detail at two momenta, q = (π, π) and (π/2, π/2). ...

**Context 5**

... the real material, the model we use is two dimensional, involves Holstein rather than cooperative JT phonons, and does not include AF couplings. As Figs.2(e)-(f) demonstrate the phonon softening at the short range ordering wavevector follows similar trends in theory and experiment roughly upto T F M , beyond which they deviate. The fractional softening near T F M however differs by more than a factor of two. ...

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