Glassiness and exotic entropy scaling induced by quantum fluctuations in a disorder-free frustrated magnet

Klich, Israel; Lee, S.-H.; Iida, Kazuki

doi:10.1038/ncomms4497

Cited by 29 publications

(65 citation statements)

References 51 publications

(68 reference statements)

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“…6 Moving away from the specific context of disorder and impurities in spin ice, our work is a small step in the general problem of quenched random disorder in highly frustrated magnetic systems. We expect that in the near future, the effects of disorder on the thermodynamic properties of other highly frustrated magnetic systems, such as the kagome materials SrCr x Ga 12−x O 19 (SCGO) [64][65][66][67] and ZnCu 3 (OH) 6 Cl 2 (Herbertsmithite), 68,69 will be particularly relevant. This is motivated by the necessity to understand whether the observed experimental behavior in SCGO and the putative quantum spin liquid Herbersmithite is intrinsic to the hypothetical disorder-free material or, instead, driven largely by disorder effects.…”

Section: Discussionmentioning

confidence: 99%

Nonmonotonic residual entropy in diluted spin ice: A comparison between Monte Carlo simulations of diluted dipolar spin ice models and experimental results

Lin

Thesberg

et al. 2014

Phys. Rev. B

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Spin ice materials, such as Dy2Ti2O7 and Ho2Ti2O7, are highly frustrated magnetic systems. Their low temperature strongly correlated state can be mapped onto the proton disordered state of common water ice. As a result, spin ices display the same low temperature residual Pauling entropy as water ice, at least in calorimetric experiments that are equilibrated over moderately long time scales. It was found in a previous study [X. Ke et. al. Phys. Rev. Lett. 99, 137203 (2007)] that, upon dilution of the magnetic rare-earth ions (Dy 3+ and Ho 3+ ) by non-magnetic Yttrium (Y 3+ ) ions, the residual entropy depends non-monotonically on the concentration of Y 3+ ions. A quantitative description of the magnetic specific heat of site-diluted spin ice materials can be viewed as a further test aimed at validating the microscopic Hamiltonian description of these systems. In the present work, we report results from Monte Carlo simulations of site-diluted microscopic dipolar spin ice models (DSIM) that account quantitatively for the experimental specific heat measurements, and thus also for the residual entropy, as a function of dilution, for both Dy2−xYxTi2O7 and Ho2−xYxTi2O7. The main features of the dilution physics displayed by the magnetic specific heat data are quantitatively captured by the diluted DSIM up to 85% of the magnetic ions diluted (x = 1.7). The previously reported departures in the residual entropy between Dy2−xYxTi2O7 versus Ho2−xYxTi2O7, as well as with a site-dilution variant of Pauling's approximation, are thus rationalized through the site-diluted DSIM. We find for 90% (x = 1.8) and 95% (x = 1.9) of the magnetic ions diluted in Dy2−xYxTi2O7 a significant discrepancy between the experimental and Monte Carlo specific heat results. We discuss possible reasons for this disagreement.

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Section: Discussionmentioning

confidence: 99%

Nonmonotonic residual entropy in diluted spin ice: A comparison between Monte Carlo simulations of diluted dipolar spin ice models and experimental results

Lin

Thesberg

et al. 2014

Phys. Rev. B

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“…Finally, at the top corner is the new magnetic state dubbed spin jam that encompasses many densely populated compounds with short-range exchange magnetic interactions, disorder and frustration. Disorder can be either extrinsic as in LSCO, FeTeSe and Na2Ir1-xTixO3, or intrinsic due to quantum fluctuations as in SCGO and BCGO 15,16 .…”

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Scaling of Memories and Crossover in Glassy Magnets

Samarakoon

Takahashi

Zhang

et al. 2017

Sci Rep

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Glassiness is ubiquitous and diverse in characteristics in nature. Understanding their differences and classification remains a major scientific challenge. Here, we show that scaling of magnetic memories with time can be used to classify magnetic glassy materials into two distinct classes. The systems studied are high temperature superconductor-related materials, spin-orbit Mott insulators, frustrated magnets, and dilute magnetic alloys. Our bulk magnetization measurements reveal that most densely populated magnets exhibit similar memory behavior characterized by a relaxation exponent of . This exponent is different from of dilute magnetic alloys that was ascribed to their hierarchical and fractal energy landscape, and is also different from of the conventional Debye relaxation expected for a spin solid, a state with long range order. Furthermore, our systematic study on dilute magnetic alloys with varying magnetic concentration exhibits crossovers among the two glassy states and spin solid.

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“…For instance, for Cu − 2 at. % Mn (CuMn2% hereafter), Θ = −45 K and = 15.5 K. Another distinct glassy state called a spin jam has been recently suggested to appear in densely populated frustrated magnets (17)(18)(19)(20)(21). At the mean-field level, these systems are expected to remain in a classical spin liquid down to absolute zero temperature, due to macroscopic classical ground state degeneracy.…”

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confidence: 99%

“…We have performed the TRM measurements on two spin jam prototypes, SCGO(p = 0.97) and BaCr9pGa12-9pO19 (BCGO)(p = 0.96) in which the magnetic Cr 3+ (3d 3 ) ions form a highly frustrating quasi-2D triangular network of bipyramids (17)(18)(19)(20)(21) and a spin glass prototype CuMn2% in which the 2% low concentration of the magnetic Mn atoms is embedded in the nonmagnetic Cu metal. Strong aging and memory effects have been observed in CuMn2%, whereas the effects are much weaker in SCGO and BCGO.…”

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Aging, memory, and nonhierarchical energy landscape of spin jam

Samarakoon

Sato

Chen

et al. 2016

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

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The notion of complex energy landscape underpins the intriguing dynamical behaviors in many complex systems ranging from polymers, to brain activity, to social networks and glass transitions. The spin glass state found in dilute magnetic alloys has been an exceptionally convenient laboratory frame for studying complex dynamics resulting from a hierarchical energy landscape with rugged funnels. Here, we show, by a bulk susceptibility and Monte Carlo simulation study, that densely populated frustrated magnets in a spin jam state exhibit much weaker memory effects than spin glasses, and the characteristic properties can be reproduced by a nonhierarchical landscape with a wide and nearly flat but rough bottom. Our results illustrate that the memory effects can be used to probe different slow dynamics of glassy materials, hence opening a window to explore their distinct energy landscapes. memory | energy landscape | spin jam | spin glass I f the energy landscape of a system resembles a smooth vase with a pointy bottom end, upon cooling the system goes quickly into the lowest energy state, i.e., the global ground state, that is usually associated with crystalline order. If the energy landscape is more complex with many metastable states, i.e., local minima, then cooling may lead the system into local minima resulting in a glassy order. The concept of such energy landscapes has been instrumental in explaining the glassiness that is ubiquitous in a wide range of systems, including atomic clusters (1), structural glasses (2, 3), polymers (4), brain activity (5), and social networks (6). Several different topological types of energy landscapes were proposed to characterize different glassiness and the associated slow dynamics (7,8). For instance, a rugged funnel-shaped landscape shown in Fig. 1A was proposed to understand the physics of biopolymers (9, 10) and dilute magnetic alloys called spin glass (11).Magnetic glass systems (12-16) present a unique opportunity to microscopically study the relation between the energy landscape and low temperature properties. The most studied magnetic glass state is the conventional spin glass realized in dilute magnetic alloys such as CuMn and AuFe. Here, dilute magnetic ions (Mn and Fe) in a nonmagnetic metal interact via the longrange Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction whose magnitude and sign change with distance between the randomly placed magnetic ions (11). The randomness drives the system into the spin glass state below a critical temperature, T f , that is comparable to the mean-field magnetic energy scale, i.e., the absolute value of the Curie-Weiss temperature, jΘ CW j. For instance, for Cu − 2 atomic (at.) % Mn (CuMn2% hereafter), Θ CW = −45 K and T f = 15.5 K. Another distinct glassy state called a spin jam has been recently suggested to appear in densely populated frustrated magnets (17-21). At the mean-field level, these systems are expected to remain in a classical spin liquid down to absolute zero temperature, due to macroscopic classical ground state dege...

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Glassiness and exotic entropy scaling induced by quantum fluctuations in a disorder-free frustrated magnet

Cited by 29 publications

References 51 publications

Nonmonotonic residual entropy in diluted spin ice: A comparison between Monte Carlo simulations of diluted dipolar spin ice models and experimental results

Nonmonotonic residual entropy in diluted spin ice: A comparison between Monte Carlo simulations of diluted dipolar spin ice models and experimental results

Scaling of Memories and Crossover in Glassy Magnets

Aging, memory, and nonhierarchical energy landscape of spin jam

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