scholarly journals The Temperature Dependence of the Magnetization Process of the Kondo Insulator YbB12

Crystals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 26 ◽  
Author(s):  
Yasuhiro H. Matsuda ◽  
Yoshiki Kakita ◽  
Fumitoshi Iga
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Condensed Matter ◽  
Characteristic Temperature ◽  
Energy Scale ◽  
Kondo Temperature ◽  
Magnetization Process ◽  
Kondo Insulator ◽  
Kondo Insulators ◽  
Order Of Magnitude

The properties of the Kondo insulator in a strong magnetic field are one of the most intriguing subjects in condensed matter physics. The Kondo insulating state is expected to be suppressed by magnetic fields, which results in the dramatic change in the electronic state. We have studied the magnetization process of one of the prototypical Kondo insulators YbB 12 at several temperatures in magnetic fields of up to 80 T. The metamagnetism due to the insulator-metal (IM) transition seen around 50 T was found to become significantly broadened at approximately 30 K. This characteristic temperature T * ≈ 30 K in YbB 12 is an order of magnitude lower than the Kondo temperature T K = 240 K. Our results suggest that there is an energy scale smaller than the Kondo temperature that is important to understanding the nature of Kondo insulators.

OBSERVATION OF A SECOND ENERGY SCALE IN YbAl3 ABOVE 40 T

2002 ◽  
Vol 16 (20n22) ◽  
pp. 2992-2997
Author(s):  
A. L. CORNELIUS ◽  
T. EBIHARA ◽  
J. M. LAWRENCE ◽  
P. S. RISEBOROUGH ◽  
J. D. THOMPSON
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Fermi Surface ◽  
Characteristic Temperature ◽  
Large Change ◽  
Energy Scale ◽  
Kondo Temperature ◽  
Field Energy ◽  
Zero Field ◽  
Effective Masses

YbAl 3 is an intermediate valent compound with a Kondo temperature T K in excess of 500 K and a rather low conduction electron density of ~0.5/atom. Recent measurements are suggestive of a second energy scale T coh of order 50 K that dominates the low temperature ( T ≪ T coh ) thermodynamic properties. Previous de Haas-van Alphen (dHvA) measurements on YbAl 3 in magnetic fields to 17 T reveal a fairly simple Fermi surface with 6 branches having effective masses m* ranging from 8 to 24 m0 (see Refs. [2-3]). We report magnetization and dHvA results on YbAl 3 in pulsed magnetic fields up to 60 T. For T ≪ T coh we indeed find that the magnetization 'crosses' over from the zero field energy scale T coh to the high temperature energy scale T K at a magnetic field B * ≈ 40 T (≈ K B T coh /μB). For B > B *, we find dHvA oscillations when magnetic field is applied along the <100>, <110> and <111> directions. For magnetic field applied along <111>, the Fermi surface changes very little for B > B*, and the effective masses are all reduced by a factor of 2-3 relative to their low field values. This is due to the large change in the characteristic temperature, which goes from T coh below B * to T K above B *. We believe this is the first work to directly observe the two energy scales and to observe the crossover in the dominant energy scale as a function of magnetic field.

scholarly journals Observations of magnetic fields in Herbig Ae/Be stars

2018 ◽  
Vol 14 (A30) ◽  
pp. 123-123
Author(s):  
Markus Schöller ◽  
Swetlana Hubrig
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
T Tauri Stars ◽  
Be Stars ◽  
T Tauri ◽  
Weak Magnetic Fields ◽  
Order Of Magnitude ◽  
Field Geometry ◽  
Herbig Ae Stars ◽  
Magnetospheric Accretion

AbstractModels of magnetically driven accretion reproduce many observational properties of T Tauri stars. For the more massive Herbig Ae/Be stars, the corresponding picture has been questioned lately, in part driven by the fact that their magnetic fields are typically one order of magnitude weaker. Indeed, the search for magnetic fields in Herbig Ae/Be stars has been quite time consuming, with a detection rate of about 10% (e.g. Alecian et al. 2008), also limited by the current potential to detect weak magnetic fields. Over the last two decades, magnetic fields were found in about twenty objects (Hubrig et al. 2015) and for only two Herbig Ae/Be stars was the magnetic field geometry constrained. Ababakr, Oudmaijer & Vink (2017) studied magnetospheric accretion in 56 Herbig Ae/Be stars and found that the behavior of Herbig Ae stars is similar to T Tauri stars, while Herbig Be stars earlier than B7/B8 are clearly different. The origin of the magnetic fields in Herbig Ae/Be stars is still under debate. Potential scenarios include the concentration of the interstellar magnetic field under magnetic flux conservation, pre-main-sequence dynamos during convective phases, mergers, or common envelope developments. The next step in this line of research will be a dedicated observing campaign to monitor about two dozen HAeBes over their rotation cycle.

scholarly journals 17. Some considerations on thermal conduction and magnetic fields in prominences

1958 ◽  
Vol 6 ◽  
pp. 150-157 ◽  
Author(s):  
S. Rosseland ◽  
E. Jensen ◽  
E. Tandberg-Hanssen
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Temperature Region ◽  
Thermal Conduction ◽  
Order Of Magnitude ◽  
Long Life

Prominences which extend into the million degree temperature region of the corona will, in the absence of magnetic fields, be heated up to temperatures of the same order of magnitude in the course of at most a few hours. A magnetic field of reasonable magnitude inside the prominence, will, however, be sufficient to cut down thermal conduction and turbulence to such an extent that the long life of some prominences seems understandable.

The lunar dynamo

Science ◽  
2014 ◽  
Vol 346 (6214) ◽  
pp. 1246753 ◽  
Author(s):  
Benjamin P. Weiss ◽  
Sonia M. Tikoo
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
The Moon ◽  
Planetary Interiors ◽  
Mechanical Stirring ◽  
Lunar Rocks ◽  
Order Of Magnitude ◽  
Global Magnetic Field ◽  
Dynamo Process ◽  
Inductive Generation

The inductive generation of magnetic fields in fluid planetary interiors is known as the dynamo process. Although the Moon today has no global magnetic field, it has been known since the Apollo era that the lunar rocks and crust are magnetized. Until recently, it was unclear whether this magnetization was the product of a core dynamo or fields generated externally to the Moon. New laboratory and spacecraft measurements strongly indicate that much of this magnetization is the product of an ancient core dynamo. The dynamo field persisted from at least 4.25 to 3.56 billion years ago (Ga), with an intensity reaching that of the present Earth. The field then declined by at least an order of magnitude by ∼3.3 Ga. The mechanisms for sustaining such an intense and long-lived dynamo are uncertain but may include mechanical stirring by the mantle and core crystallization.

Absorption Component of the Magnetic Susceptibility in Superconducting YBa2Cu3O7

1987 ◽  
Vol 99 ◽  
Author(s):  
R. Durny ◽  
S. Ducharme ◽  
J. Hautala ◽  
O. G. Symko ◽  
P. C. Taylor ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Magnetic Fields ◽  
Characteristic Temperature ◽  
Zero Magnetic Field ◽  
Zero Field ◽  
Dc Voltage ◽  
Absorption Component ◽  
Field Dependent ◽  
Absorption Measurements

ABSTRACTMicrowave absorption measurements from 20 to 80 K in magnetic fields up to 12 kG are reported. Below a certain characteristic temperature T* = 80 ± 2 K < Tc the absorption in magnetic-field-cooled samples is smaller and broader in comparison to the zero-field-cooled samples. The incident microwave radiation induces a dc voltage across the sample which is also magnetic field dependent and peaks at zero magnetic field.

Matter in superstrong magnetic fields

1986 ◽  
Vol 64 (3) ◽  
pp. 256-268 ◽  
Author(s):  
J. E. Skjervold ◽  
E. Østgaard
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Variational Method ◽  
Cohesive Energy ◽  
Condensed Matter ◽  
Binding Energies ◽  
Free Atoms ◽  
The Difference ◽  
Cohesive Energies

The behaviour of condensed matter in superstrong magnetic fields of the order of 1012–1015 G is investigated, i.e., binding energies of atoms in condensed matter are calculated by a variational method. The cohesive energy, i.e., the difference between the binding energies of free atoms and of atoms in condensed matter, is also calculated, and results are obtained for hydrogen, helium, carbon, oxygen, silicon, and iron atoms.For a magnetic field of 1012 G, we obtain binding energies for atoms in condensed matter of 0.2 keV for hydrogen, 0.7 keV for helium, 4.5 keV for carbon, 7.4 keV for oxygen, 20.0 keV for silicon, and 59.0 keV for iron. For a magnetic field of 1014 G, we get corresponding binding energies of 1.2 keV for hydrogen, 3.9 keV for helium, 27.0 keV for carbon, 44.9 keV for oxygen, 121.5 keV for silicon, and 366 keV for iron. For a magnetic field of 1012 G, we obtain cohesive energies of 0.04 keV for hydrogen, 0.10 keV for helium, 0.36 keV for carbon, 0.51 keV for oxygen, 1.4 keV for silicon, and 2.8 keV for iron. For a magnetic field of 1014 G, we get corresponding cohesive energies of 0.16 keV for hydrogen, 0.40 keV for helium, 1.9 keV for carbon, 3.0 keV for oxygen, 7.3 keV for silicon, and 19.4 keV for iron.

scholarly journals Magnetization Process of the Kondo Insulator YbB12 in Ultrahigh Magnetic Fields

2017 ◽  
Vol 86 (5) ◽  
pp. 054710 ◽  
Author(s):  
Taku T. Terashima ◽  
Akihiko Ikeda ◽  
Yasuhiro H. Matsuda ◽  
Akihiro Kondo ◽  
Koichi Kindo ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Magnetization Process ◽  
Kondo Insulator ◽  
Ultrahigh Magnetic Fields

The role of magnetic fields in the early stages of star formation

2018 ◽  
Vol 14 (A30) ◽  
pp. 113-114
Author(s):  
Maud Galametz ◽  
Anaëlle Maury ◽  
Valeska Valdivia
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Magnetic Fields ◽  
Large Scale ◽  
Polarized Emission ◽  
Order Of Magnitude ◽  
Low Mass ◽  
Geometrical Effects ◽  
The Magnetic Field

AbstractMagnetic fields are believed to redistribute part of the angular momentum during the collapse and could explain the order-of-magnitude difference between the angular momentum observed in protostellar envelopes and that of a typical main sequence star. The Class 0 phase is the main accretion phase during which most of the final stellar material is collected on the central embryo. To study the structure of the magnetic fields on 50-2000 au scales during that key stage, we acquired SMA polarization observations (870μm) of 12 low-mass Class 0 protostars. In spite of their low luminosity, we detect dust polarized emission in all of them. We observe depolarization effects toward high-density regions potentially due to variations in alignment efficiency or in the dust itself or geometrical effects. By comparing the misalignment between the magnetic field and the outflow orientation, we show that the B is either aligned or perpendicular to the outflow direction. We observe a coincidence between the misalignment and the presence of large perpendicular velocity gradients and fragmentation in the protostar (Galametz et al. 2018). Our team is using MHD simulations combined with the radiative transfer code POLARIS to produce synthetic maps of the polarized emission. This work is helping us understand how the magnetic field varies from the large-scale to the small-scales, quantify beam-averaging biases and study the variations of the polarization angles as a function of wavelength or the assumption made on the grain alignment (see poster by Valdivia).

scholarly journals Magnetic field-tuned Fermi liquid in a Kondo insulator

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Satya K. Kushwaha ◽  
Mun K. Chan ◽  
Joonbum Park ◽  
S. M. Thomas ◽  
Eric D. Bauer ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Spin ◽  
Fermi Liquid ◽  
Critical Magnetic Field ◽  
Quantum Criticality ◽  
Kondo Insulator ◽  
Kondo Insulators ◽  
Insulator Metal Transition ◽  
Insulating Gap ◽  
The Magnetic Field

AbstractKondo insulators are expected to transform into metals under a sufficiently strong magnetic field. The closure of the insulating gap stems from the coupling of a magnetic field to the electron spin, yet the required strength of the magnetic field–typically of order 100 T–means that very little is known about this insulator-metal transition. Here we show that Ce$${}_{3}$$3Bi$${}_{4}$$4Pd$${}_{3}$$3, owing to its fortuitously small gap, provides an ideal Kondo insulator for this investigation. A metallic Fermi liquid state is established above a critical magnetic field of only $${B}_{{\rm{c}}}\approx$$Bc≈ 11 T. A peak in the strength of electronic correlations near $${B}_{{\rm{c}}}$$Bc, which is evident in transport and susceptibility measurements, suggests that Ce$${}_{3}$$3Bi$${}_{4}$$4Pd$${}_{3}$$3 may exhibit quantum criticality analogous to that reported in Kondo insulators under pressure. Metamagnetism and the breakdown of the Kondo coupling are also discussed.

scholarly journals Resistivity saturation in Kondo insulators

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Matthias Pickem ◽  
Emanuele Maggio ◽  
Jan M. Tomczak
Keyword(s):  
Characteristic Temperature ◽  
Surface States ◽  
External Pressure ◽  
Energy Scale ◽  
Metallic Surface ◽  
Bulk Property ◽  
Alternative Mechanism ◽  
Saturation Regime ◽  
Kondo Insulator ◽  
Quantum Regime

AbstractResistivities of heavy-fermion insulators typically saturate below a characteristic temperature T*. For some, metallic surface states, potentially from a non-trivial bulk topology, are a likely source of residual conduction. Here, we establish an alternative mechanism: at low temperature, in addition to the charge gap, the scattering rate turns into a relevant energy scale, invalidating the semi-classical Boltzmann picture. Then, finite lifetimes of intrinsic carriers drive residual conduction, impose the existence of a crossover T*, and control—now on par with the gap—the quantum regime emerging below it. Assisted by realistic many-body simulations, we showcase the mechanism for the Kondo insulator Ce3Bi4Pt3, for which residual conduction is a bulk property, and elucidate how its saturation regime evolves under external pressure and varying disorder. Deriving a phenomenological formula for the quantum regime, we also unriddle the ill-understood bulk conductivity of SmB6—demonstrating a wide applicability of our mechanism in correlated narrow-gap semiconductors.

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