Effect of Biaxial Strain on the Phase Transitions of 
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Böhmer, Anna E.; Sapkota, A.; Kreyßig, A.; Bud’ko, Sergey L.; Drachuck, Gil; Saunders, Scott M.; Goldman, A. I.; Canfield, Paul C.

doi:10.1103/physrevlett.118.107002

Cited by 29 publications

(35 citation statements)

References 42 publications

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“…In-plane strain has previously been demonstrated as suitable means to induce phase transitions 36 . Here we have shown how a complete symmetry decomposition, made possible by comparison to hydrostatic pressure, reveals the separate effects of symmetric and antisymmetric strains that are necessarily both present when a sample is held under in-plane uniaxial stress.…”

Section: Discussionmentioning

confidence: 99%

Symmetric and antisymmetric strain as continuous tuning parameters for electronic nematic order

et al. 2018

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We report the separate response of the critical temperature of the nematic phase transition TS to symmetric and antisymmetric strains for the prototypical underdoped iron pnictide Ba(Fe0.975Co0.025)2As2. This decomposition is achieved by comparing the response of TS to inplane uniaxial stress and hydrostatic pressure. In addition to quantifying the two distinct linear responses to symmetric strains, we find a quadratic variation of TS as a response to antisymmetric strains εB 1g = 1 2 (εxx-εyy), exceeding the non linear response to symmetric strains by at least two orders of magnitude. These observations establish orthogonal antisymmetric strain as a powerful tuning parameter for nematic order.In this paper we demonstrate how this can be achieved

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Section: Discussionmentioning

confidence: 99%

Symmetric and antisymmetric strain as continuous tuning parameters for electronic nematic order

et al. 2018

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“…• C, which ensured an ambient pressure T (uncollapsed) phase at all temperatures [20,29]. INS measurements were carried out on 10 and 14 coaligned single crystals, for x = 0.026 and 0.030, respectively.…”

Section: Methodsmentioning

confidence: 99%

Doping evolution of spin fluctuations and their peculiar suppression at low temperatures in Ca(Fe1−xCox)2As2
Sapkota¹,
Das²,
Böhmer³
et al. 2018
Phys. Rev. B
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Results of inelastic neutron scattering measurements are reported for two annealed compositions of Ca(Fe1-xCox)(2)As-2, x = 0.026 and 0.030, which possess stripe-type antiferromagnetically ordered and superconducting ground states, respectively. In the AFM ground state, well-defined and gapped spin waves are observed for x = 0.026, similar to the parent CaFe2As2 compound. We conclude that the well-defined spin waves are likely to be present for all x corresponding to the AFM state. This behavior is in contrast to the smooth evolution to overdamped spin dynamics observed in Ba(Fe1-xCox)(2)As-2, wherein the crossover corresponds to microscopically coexisting AFM order and SC at low temperature. The smooth evolution is likely absent in Ca(Fe1-xCox)(2)As-2 due to the mutual exclusion of AFM ordered and SC states. Overdamped spin dynamics characterize paramagnetism of the x = 0.030 sample and high-temperature x = 0.026 sample. A sizable loss of magnetic intensity is observed over a wide energy range upon cooling the x = 0.030 sample, at temperatures just above and within the superconducting phase. This phenomenon is unique amongst the iron-based superconductors and is consistent with a temperature-dependent reduction in the fluctuating moment. One possible scenario ascribes this loss of moment to a sensitivity to the c-axis lattice parameter in proximity to the nonmagnetic collapsed tetragonal phase and another scenario ascribes the loss to a formation of a pseudogap. Results of inelastic neutron scattering measurements are reported for two annealed compositions of Ca(Fe 1−x Co x ) 2 As 2 , x = 0.026 and 0.030, which possess stripe-type antiferromagnetically ordered and superconducting ground states, respectively. In the AFM ground state, well-defined and gapped spin waves are observed for x = 0.026, similar to the parent CaFe 2 As 2 compound. We conclude that the well-defined spin waves are likely to be present for all x corresponding to the AFM state. This behavior is in contrast to the smooth evolution to overdamped spin dynamics observed in Ba(Fe 1−x Co x ) 2 As 2 , wherein the crossover corresponds to microscopically coexisting AFM order and SC at low temperature. The smooth evolution is likely absent in Ca(Fe 1−x Co x ) 2 As 2 due to the mutual exclusion of AFM ordered and SC states. Overdamped spin dynamics characterize paramagnetism of the x = 0.030 sample and high-temperature x = 0.026 sample. A sizable loss of magnetic intensity is observed over a wide energy range upon cooling the x = 0.030 sample, at temperatures just above and within the superconducting phase. This phenomenon is unique amongst the iron-based superconductors and is consistent with a temperature-dependent reduction in the fluctuating moment. One possible scenario ascribes this loss of moment to a sensitivity to the c-axis lattice parameter in proximity to the nonmagnetic collapsed tetragonal phase and another scenario ascribes the loss to a formation of a pseudogap. Disciplines Condensed Matter Physics | Physics

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Section: Discussionmentioning

confidence: 66%

“…The c-axis pressure-induced AF order we observed in BaFe 2 (As 0.70 P 0.30 ) 2 is in someways reminiscent of the effect of biaxial strain on the phase transitions in Ca(Fe 1−x Co x ) 2 As 2 [63,64]. Similar to c-axis uniaxial pressure, biaxial in-plane strain achieved by using the differential thermal expansion between the samples and a rigid substrate affects the c/a ratio of the tetragonal samples but does not break the tetragonal symmetry [63]. Instead of decreasing the c/a ratio by applying a c-axis pressure, biaxial in-plane strain in Ca(Fe 1−x Co x ) 2 As 2 increases the c/a ratio and shifts the phase diagram of Ca(Fe 1−x Co x ) 2 As 2 to higher x, without changing the maximum T c and magnetic phase transition temperature [63].…”

Section: Discussionmentioning

confidence: 66%

“…Similar to c-axis uniaxial pressure, biaxial in-plane strain achieved by using the differential thermal expansion between the samples and a rigid substrate affects the c/a ratio of the tetragonal samples but does not break the tetragonal symmetry [63]. Instead of decreasing the c/a ratio by applying a c-axis pressure, biaxial in-plane strain in Ca(Fe 1−x Co x ) 2 As 2 increases the c/a ratio and shifts the phase diagram of Ca(Fe 1−x Co x ) 2 As 2 to higher x, without changing the maximum T c and magnetic phase transition temperature [63]. Here, the quantum phase transition between the superconducting tetragonal and AF orthorhombic phases is first-order, and the resulting phase separation into these two phases with different in-plane lattice parameters allows the material to respond to biaxial strain in a continuous fashion [64].…”

Section: Discussionmentioning

confidence: 99%

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c-axis pressure-induced antiferromagnetic order in optimally P-doped BaFe2(As0.70P0.30)2 superconductor

Wang

Zhang

et al. 2018

npj Quant Mater

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Superconductivity in BaFe 2 (As 1−x P x ) 2 iron pnictides emerges when its in-plane two-dimensional (2D) orthorhombic lattice distortion associated with nematic phase at T s and three-dimensional (3D) collinear antiferromagnetic (AF) order at T N (T s = T N ) are gradually suppressed with increasing x, reaching optimal superconductivity around x = 0.30 with T c ≈ 30 K. Here we show that a moderate uniaxial pressure along the c-axis in BaFe 2 (As 0.70 P 0.30 ) 2 spontaneously induces a 3D collinear AF order with T N = T s > 30 K, while only slightly suppresses T c . Although a ∼400 MPa pressure compresses the c-axis lattice while expanding the in-plane lattice and increasing the nearest-neighbor Fe-Fe distance, it barely changes the average iron-pnictogen height in BaFe 2 (As 0.70 P 0.30 ) 2 . Therefore, the pressureinduced AF order must arise from a strong in-plane magnetoelastic coupling, suggesting that the 2D nematic phase is a competing state with superconductivity. arXiv:1808.05153v1 [cond-mat.supr-con]

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Effect of Biaxial Strain on the Phase Transitions of Ca(Fe1−xCox)

Cited by 29 publications

References 42 publications

Symmetric and antisymmetric strain as continuous tuning parameters for electronic nematic order

Symmetric and antisymmetric strain as continuous tuning parameters for electronic nematic order

Doping evolution of spin fluctuations and their peculiar suppression at low temperatures in Ca(Fe1−xCox)2As2
Sapkota¹,
Das²,
Böhmer³
et al. 2018
Phys. Rev. B
Self Cite
7
2
12
0
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c-axis pressure-induced antiferromagnetic order in optimally P-doped BaFe2(As0.70P0.30)2 superconductor

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Effect of Biaxial Strain on the Phase Transitions of Ca(Fe1−xCox)

Cited by 29 publications

References 42 publications

Symmetric and antisymmetric strain as continuous tuning parameters for electronic nematic order

Symmetric and antisymmetric strain as continuous tuning parameters for electronic nematic order

Doping evolution of spin fluctuations and their peculiar suppression at low temperatures in Ca(Fe1−xCox)2As2Sapkota1, Das2, Böhmer3 et al. 2018Phys. Rev. BSelf Cite72120View full textAdd to dashboardCite

c-axis pressure-induced antiferromagnetic order in optimally P-doped BaFe2(As0.70P0.30)2 superconductor

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Doping evolution of spin fluctuations and their peculiar suppression at low temperatures in Ca(Fe1−xCox)2As2
Sapkota¹,
Das²,
Böhmer³
et al. 2018
Phys. Rev. B
Self Cite
7
2
12
0
View full text Add to dashboard Cite