Diffraction line-shapes, Fermi surface nesting, and quantum criticality in antiferromagnetic chromium at high pressure (invited)

Jaramillo, Rafael; Feng, Yejun; Rosenbaum, T. F.

doi:10.1063/1.3364062

Cited by 4 publications

(2 citation statements)

References 21 publications

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“…As a function of pressure, however, this BCS-like theory accurately describes the observed exponential dependence of both the phase boundary T N ðPÞ and the saturated order parameter at low temperature (19,20). The exponential evolution results from a competition between exchange energy and bandwidth that is tuned by applied pressure while preserving the Fermi surface nesting condition (21). Above 7 GPa the exponential ground state breaks down and the phase diagram approaches the QPT.…”

Section: Discussionmentioning

confidence: 99%

Signatures of quantum criticality in pure Cr at high pressure

Jaramillo

Feng

Wang

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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The elemental antiferromagnet Cr at high pressure presents a new type of naked quantum critical point that is free of disorder and symmetry-breaking fields. Here we measure magnetotransport in fine detail around the critical pressure, P c ∼ 10 GPa, in a diamond anvil cell and reveal the role of quantum critical fluctuations at the phase transition. As the magnetism disappears and T → 0, the magntotransport scaling converges to a non-mean-field form that illustrates the reconstruction of the magnetic Fermi surface, and is distinct from the critical scaling measured in chemically disordered Cr∶V under pressure. The breakdown of itinerant antiferromagnetism only comes clearly into view in the clean limit, establishing disorder as a relevant variable at a quantum phase transition.antiferromagnetism | spin density waves | electric transport C ompetition between magnetic and nonmagnetic states of matter in the zero-temperature limit underlies the emergence of exotic ground states such as non-Fermi liquid metals and unconventional superconductors (1). This observation has motivated several decades of work to understand the physics of magnetic quantum phase transitions (QPT) (2-7). A substantial part of the effort has been directed at the materials science challenges that are inherent to realizing nearly-magnetic states of matter and to the fine tuning of materials so that the phase transitions can be probed systematically. The fundamental limitations that remain are uncertainty over the role of disorder (2,4,8), as well as a predilection for first-order transitions that shroud the quantum critical behavior (3, 5). Recent X-ray measurements identified a continuous disappearance of magnetic order in the elemental antiferromagnet Cr near the critical pressure P c ∼ 10 GPa, and concurrent measurements of the crystal lattice across the transition failed to detect any discontinuous change in symmetry or volume (9). These results identify Cr as a stoichiometric itinerant magnet with a continuous QPT-where the effects of the critical point should be manifest-and present a rare opportunity to study quantum criticality in a theoretically tractable system that is free from the effects of disorder. Moreover, the use of hydrostatic pressure as a tuning parameter avoids the introduction of any confounding symmetry-breaking fields.For the experimentalist, studying elemental Cr shifts the significant technical difficulties from solid state chemistry to high pressure experimentation. Here we report on high-resolution measurements of the electrical resistivity and Hall coefficient of Cr as the system is tuned with pressure in a diamond anvil cell across P c . Magnetotransport is a sensitive probe of quantum criticality and is widely used to identify and characterize quantum matter (4,5,8,10). At ambient pressure Cr orders antiferromagnetically at the Néel temperature, T N ðP ¼ 0Þ ¼ 311 K. Below T N , electrons and holes form magnetic pairs and condense into a spin density wave (SDW), in a process with strong analogies to the Bardeen-Coo...

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Section: Discussionmentioning

confidence: 99%

Signatures of quantum criticality in pure Cr at high pressure

Jaramillo

Feng

Wang

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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“…While a lower limit 27 for domains in β − Na 0.33 V 2 O 5 is 1000Å. Whereas the correlation length 28 as measured by X-rays diffraction at 5K in Cr is well over 2000Å. In contrast to NbSe 3 for o − TaS 3 the correlation length can be roughly estimated from X-rays measurements 29 at about 500Å.…”

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confidence: 88%

Experimental consequences of quantum critical points at high temperatures

et al. 2015

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We study the 𝐶𝑟 !!! 𝑅𝑒 ! phase diagram finding that its phase transition temperature towards an antiferromagnetic order 𝑇 ! follows a quantum 𝑥 ! − 𝑥 /𝑥 ! ! law, with 𝜓 = 1/2, from the quantum critical point (QCP) at 𝑥 ! = 0.25 up to 𝑇 ! ≈ 600𝐾. We compare this system to others in order to understand why this elemental material is affected by the QCP up to such unusually high temperatures. We determine a general criterion for the crossover, as function of an external parameter such as concentration, from the region controlled solely by thermal fluctuations to that where quantum effects become observable. The properties of materials with low coherence lengths will thus be altered far away from the QCP.

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Low temperature and magnetic field behaviour of the (Cr84Re16)89.6V10.4 alloy

Jacobs

Sheppard

Prinsloo

et al. 2014

Journal of Applied Physics

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Measurements of the temperature (T) dependence of the magnetic susceptibility (χ) and electrical resistance (R) on an antiferromagnetic (AFM) (Cr84Re16)89.6V10.4 alloy are reported in order to probe the existence of quantum critical behaviour (QCB) utilizing static magnetic fields (H) as a tuning parameter. The results indicate that an increase in H suppresses TN in such a way that it varies exponentially with increasing H. R(T) measurements show evidence of possible superconducting (SC) behaviour below 1 K at H = 0 T. These results therefore indicate the coexistence of the AFM and SC phases in the (Cr84Re16)89.6V10.4 alloy.

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Diffraction line-shapes, Fermi surface nesting, and quantum criticality in antiferromagnetic chromium at high pressure (invited)

Abstract: Articles you may be interested inSimilarity between the effects of pressure and electron concentration on the magnetic behavior of a Cr+0.2 at.% Ir alloy

Cited by 4 publications

References 21 publications

Signatures of quantum criticality in pure Cr at high pressure

Signatures of quantum criticality in pure Cr at high pressure

Experimental consequences of quantum critical points at high temperatures

Low temperature and magnetic field behaviour of the (Cr84Re16)89.6V10.4 alloy

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