arXiv subjects

Keisuke Sato

Publications and source records attributed to Keisuke Sato.

12 recordsLinked to original sources

arXiv2024

The Honorific Effect: Exploring the Impact of Japanese Linguistic Formalities on AI-Generated Physics Explanations

This study investigates the influence of Japanese honorifics on the responses of large language models (LLMs) when explaining the law of conservation of momentum. We analyzed the outputs of six state-of-the-art AI models, including variations of ChatGPT, Coral, and Gemini, using 14 different honorific forms. Our findings reveal that honorifics significantly affect the quality, consistency, and formality of AI-generated responses, demonstrating LLMs' ability to interpret and adapt to social context cues embedded in language. Notable variations were observed across different models, with some emphasizing historical context and derivations, while others focused on intuitive explanations. The study highlights the potential for using honorifics to adjust the depth and complexity of AI-generated explanations in educational contexts. Furthermore, the responsiveness of AI models to cultural linguistic elements underscores the importance of considering cultural factors in AI development for educational applications. These results open new avenues for research in AI-assisted education and cultural adaptation in AI systems, with significant implications for personalizing learning experiences and developing culturally sensitive AI tools for global education.

physics.ed-ph↗

arXiv2024

Exploring the Educational Landscape of AI: Large Language Models' Approaches to Explaining Conservation of Momentum in Physics

The integration of Large Language Models (LLMs) in education offers both opportunities and challenges, particularly in fields like physics that demand precise conceptual understanding. This study examines the capabilities of six state-of-the-art LLMs in explaining the law of conservation of momentum, a fundamental principle in physics. By analyzing responses to a consistent, simple prompt in Japanese, we assess the models' explanatory approaches, depth of understanding, and adaptability to different educational levels.Our comprehensive analysis, encompassing text characteristics, response similarity, and keyword usage, unveils significant diversity in explanatory styles across models. ChatGPT4.0 and Coral provided more comprehensive and technically detailed explanations, while Gemini models tended toward more intuitive approaches. Key findings include variations in the treatment of critical concepts such as net force, and differing emphases on mathematical rigor and real-world applications.The results indicate that different AI models may be more suitable for various educational contexts, ranging from introductory to advanced levels. ChatGPT4.0 and Coral demonstrated potential for advanced discussions, while Gemini models appeared more appropriate for introductory explanations. Importantly, the study underscores the necessity of educator guidance in effectively leveraging these AI tools, as models varied in their ability to convey nuanced aspects of physical principles.This research establishes a foundation for understanding the educational potential of LLMs in physics, providing insights for educators on integrating these tools into their teaching practices. It also highlights the need for further investigation into AI-assisted learning in STEM fields, paving the way for more sophisticated applications of AI in physics education.

physics.ed-ph↗

arXiv2024

A review on magnetic field induced spin crossover in LaCoO$_{3}$ up to 600 T

\lco{} is known for its two-step spin crossover as a function of temperature. Despite efforts spanning over half a century, the origin of this phenomenon is still debated, particularly regarding how the microscopic spin states are involved in the observed macroscopic two-step spin crossover. High magnetic field studies on LaCoO$_{3}$ are performed because the magnetic field-induced spin crossover is induced, where the magnetic excited states become more stable in high magnetic fields than the non-magnetic ground states. This review focuses on the findings in LaCoO$_{3}$ at high magnetic fields over the last decade. A complex phase diagram has been revealed at high magnetic fields instead of solving the conventional problem of LaCoO$_{3}$. It suggests that appreciable spin state correlations are in play in LaCoO$_{3}$. The possibility of exciton condensation is also discussed.

cond-mat.str-el↗

arXiv2023

Signature of spin-triplet exciton condensations in LaCoO$_{3}$ at ultrahigh magnetic fields up to 600 T

Bose-Einstein condensation of electron-hole pairs, exciton condensation, has been effortfully investigated since predicted 60 years ago. Irrefutable evidence has still been lacking due to experimental difficulties in verifying the condensation of the charge neutral and non-magnetic spin-singlet excitons. Whilst, condensation of spin-triplet excitons is a promising frontier because spin supercurrent and spin-Seebeck effects will be observable. A canonical cobaltite LaCoO$_{3}$ under very high magnetic fields is a propitious candidate, yet to be verified. Here, we unveil the exotic phase diagram of LaCoO$_{3}$ up to 600 T generated using the electromagnetic flux compression method and the state-of-the-art magnetostriction gauge. We found the continuous magnetostriction curves and a bending structure, which suggest the emergence of two distinct spin-triplet exciton condensates. By constructing a phenomenological model, we showed that quantum fluctuations of excitons are crucial for the field-induced successive transitions. The spin-triplet exciton condensation in a cobaltite, which is three-dimensional and thermally equilibrated, opens up a novel venue for spintronics technologies with spin-supercurrent such as a spin Josephson junction.

cond-mat.str-el↗

arXiv2020

Two Spin-State Crystallizations in LaCoO$_{3}$

We report a magnetostriction study of a perovskite $\rm{LaCoO}_{3}$ above 100 T using our state-of-the-art strain gauge to investigate an interplay between electron correlations and spin crossover. There has been a controversy regarding whether two novel phases in $\rm{LaCoO}_{3}$ at high magnetic fields result from crystallizations or Bose-Einstein condensation during spin crossover as manifestations of localization and delocalization in spin states, respectively. We show that both phases are crystallizations rather than condensations, and the two crystallizations are different, based on the observations that the two phases exhibit as magnetostriction plateaux with distinct heights. The crystallizations of spin states have emerged manifesting the localizations and interactions in spin crossover with large and cooperative lattice changes.

cond-mat.str-el↗

arXiv2019

Magnetostriction studies up to megagauss fields using fiber Bragg grating technique

We here report magnetostriction measurements under pulsed megagauss fields using a high-speed 100 MHz strain monitoring system devised using fiber Bragg grating (FBG) technique with optical filter method. The optical filter method is a detection scheme of the strain of FBG, where the changing Bragg wavelength of the FBG reflection is converted to the intensity of reflected light to enable the 100 MHz measurement. In order to show the usefulness and reliability of the method, we report the measurements for solid oxygen, spin-controlled crystal, and volborthite, a deformed Kagomé quantum spin lattice, using static magnetic fields up to 7 T and non-destructive millisecond pulse magnets up to 50 T. Then, we show the application of the method for the magnetostriction measurements of CaV$_{4}$O$_{9}$, a two-dimensional antiferromagnet with spin-halves, and LaCoO$_{3}$, an anomalous spin-crossover oxide, in the megagauss fields.

cond-mat.mtrl-sci↗

arXiv2017

100 MHz high-speed strain monitor using fiber Bragg grating and optical filter applied for magnetostriction measurements of cobaltite at magnetic fields beyond 100 T

High-speed 100 MHz strain monitor using fiber Bragg grating (FBG) and an optical filter has been devised for the magnetostriction measurements under ultrahigh magnetic fields. The longitudinal magnetostriction of LaCoO$_{3}$ has been measured at room temperature, 115, 7 and 4.2 K up to the maximum magnetic field of 150 T. The field-induced lattice elongations are observed, which are attributed to the spin-state crossover from the low-spin ground state to excited spin-states.

cond-mat.mtrl-sci↗

arXiv2017

A branch-and-price approach with MILP formulation to modularity density maximization on graphs

For clustering of an undirected graph, this paper presents an exact algorithm for the maximization of modularity density, a more complicated criterion to overcome drawbacks of the well-known modularity. The problem can be interpreted as the set-partitioning problem, which reminds us of its integer linear programming (ILP) formulation. We provide a branch-and-price framework for solving this ILP, or column generation combined with branch-and-bound. Above all, we formulate the column generation subproblem to be solved repeatedly as a simpler mixed integer linear programming (MILP) problem. Acceleration techniques called the set-packing relaxation and the multiple-cutting-planes-at-a-time combined with the MILP formulation enable us to optimize the modularity density for famous test instances including ones with over 100 vertices in around four minutes by a PC. Our solution method is deterministic and the computation time is not affected by any stochastic behavior. For one of them, column generation at the root node of the branch-and-bound tree provides a fractional upper bound solution and our algorithm finds an integral optimal solution after branching.

cs.SI↗

arXiv2017

High-speed 100 MHz strain monitor using fiber Bragg grating and optical filter for magnetostriction measurements under ultrahigh magnetic fields

A high-speed 100 MHz strain monitor using a fiber Bragg grating, an optical filter, and a mode-locked optical fiber laser has been devised, which has a resolution of $ΔL/L\sim10^{-4}$. The strain monitor is sufficiently fast and robust for the magnetostriction measurements of magnetic materials under ultrahigh magnetic fields generated with destructive pulse magnets, where the sweep rate is in the range of 10-100 T/$μ$s. As a working example, the magnetostriction of LaCoO$_{3}$ was measured at room temperature, 115 K, and 7$\sim$4.2 K up to a maximum magnetic field of 150 T. The smooth $B^{2}$ dependence and the first-order transition were observed at 115 K and 7$\sim$4.2 K, respectively, reflecting the field-induced spin-state evolution.

cond-mat.mtrl-sci↗

arXiv2016

Spin state ordering of strongly correlating LaCoO$_{3}$ induced at ultrahigh magnetic fields

Magnetization measurements of LaCoO$_{3}$ have been carried out up to 133 T generated with a destructive pulse magnet at a wide temperature range from 2 to 120 K. A novel magnetic transition was found at $B>100$ T and $T>T^{*}=32\pm 5$ K which is characterized by its transition field increasing with increasing temperature. At $T<T^{*}$, the previously reported transition at $B\sim65$ T was observed. Based on the obtained $B$-$T$ phase diagram and the Clausius-Clapeyron relation, the entropy of the high-field phase at 80 K is found to be smaller for about $1.5$ J K$^{-1}$ mol$^{-1}$ than that of the low-field phase. We suggest that the observed two high-field phases may originate in different spatial orders of the spin states and possibly other degrees of freedom such as orbitals. An inherent strong correlation of spin states among cobalt sites should have triggered the emergence of the ordered phases in LaCoO$_{3}$ at high magnetic fields.

cond-mat.str-el↗

arXiv2014

Thermal Conductivity of Simple Liquids:Origin of Temperature and Packing Fraction Dependences

The origin of both weak temperature dependence and packing fraction dependence of $T^{1/4}η^{3/2}$ in the thermal conductivity of the simple Lennard-Jones (LJ) liquid is explored. In order to discuss the relative contributions from attractive or repulsive part of the interaction potential separately, the thermal conductivity of a series of Weeks-Chandler-Anderson (WCA) fluids is calculated by molecular dynamics simulations. The results show that the repulsive part plays the main role in the heat conduction, while the attractive part has no direct effect on the thermal conductivity for a given packing fraction. By investigating WCA fluids with potentials of varying softness, we explain the difference observed between the LJ liquids such as argon and Coulombic liquids such as NaCl.

cond-mat.stat-mech↗

arXiv2010

Interplay between quantum criticality and geometrical frustration in Fe3Mo3N with stella quadrangula lattice

In the eta-carbide-type correlated-electron metal Fe3Mo3N, ferromagnetism is abruptly induced from a nonmagnetic non-Fermi-liquid ground state either when a magnetic field (~14 T) applied to it or when it is doped with a slight amount of impurity (~5% Co). We observed a peak in the paramagnetic neutron scattering intensity at finite wave vectors, revealing the presence of the antiferromagnetic (AF) correlation hidden in the magnetic measurements. It causes a new type of geometrical frustration in the stellla quadrangula lattice of the Fe sublattice. We propose that the frustrated AF correlation suppresses the F correlation to its marginal point and is therfore responsible for the origin of the ferromagnetic (F) quantum critical behavior in pure Fe3Mo3N.

cond-mat.str-el↗