The 11-year solar magnetic cycle shows a high degree of coherence in spite of the turbulent nature of the solar convection zone. It has been found in recent high-resolution magnetohydrodynamics simulations that the maintenance of a large-scale coherent magnetic field is difficult with small viscosity and magnetic diffusivity (≲10 (12) square centimenters per second). We reproduced previous findings that indicate a reduction of the energy in the large-scale magnetic field for lower diffusivities and demonstrate the recovery of the global-scale magnetic field using unprecedentedly high resolution. We found an efficient small-scale dynamo that suppresses small-scale flows, which mimics the properties of large diffusivity. As a result, the global-scale magnetic field is maintained even in the regime of small diffusivities-that is, large Reynolds numbers.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1126/science.aad1893 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Quantum Thermodynamic Derivation of the Energy Resolution Limit in Magnetometry.
Phys Rev Lett
December 2024
University of Crete, Department of Physics, Heraklion 70013, Greece.
It was recently demonstrated that a multitude of realizations of several magnetic sensing technologies satisfy the energy resolution limit, which connects a quantity composed by the variance of the magnetic field estimate, the sensor volume and the measurement time, and having units of action, with ℏ. A first-principles derivation of this limit is still elusive. We here present such a derivation based on quantum thermodynamic arguments.
View Article and Find Full Text PDFGranular Aluminum Parametric Amplifier for Low-Noise Measurements in Tesla Fields.
Phys Rev Lett
December 2024
Karlsruhe Institute of Technology, IQMT, 76131 Karlsruhe, Germany.
Josephson junction parametric amplifiers have become essential tools for microwave quantum circuit readout with minimal added noise. Even after improving at an impressive rate in the past decade, they remain vulnerable to magnetic fields, which limits their use in many applications such as spin qubits, Andreev and molecular magnet devices, dark matter searches, etc. Kinetic inductance materials, such as granular aluminum (grAl), offer an alternative source of nonlinearity with innate magnetic field resilience.
View Article and Find Full Text PDFQuasi-Two-Dimensional Antiferromagnetic Spin Fluctuations in the Spin-Triplet Superconductor Candidate CeRh_{2}As_{2}.
Phys Rev Lett
December 2024
Johns Hopkins University, Institute for Quantum Matter and Department of Physics and Astronomy, Baltimore, Maryland 21218, USA.
The tetragonal heavy-fermion superconductor CeRh_{2}As_{2} (T_{c}=0.3 K) exhibits an exceptionally high critical field of 14 T for B∥c. It undergoes a field-driven first-order phase transition between superconducting states, potentially transitioning from spin-singlet to spin-triplet superconductivity.
View Article and Find Full Text PDFDressed Majorana Fermion in a Hybrid Nanowire.
Phys Rev Lett
December 2024
Beijing Computational Science Research Center, Beijing 100193, China.
In hybrid systems where nanowires are proximity-coupled with superconductors, the low-energy theory fails to determine the topological phase with Majorana fermion (MF) when the magnetic field or proximity coupling is much stronger. To overcome this limitation, we propose a holistic approach that defines MF by considering both the motion of electrons in the nanowire and the quasiparticle excitations in the superconductor. This approach transcends the constraints of low-energy theory and offers broad applicability.
View Article and Find Full Text PDFPhase Switch Driven by the Hidden Half-Ice, Half-Fire State in a Ferrimagnet.
Phys Rev Lett
December 2024
Brookhaven National Laboratory, Condensed Matter Physics and Materials Science Division, Upton, New York 11973, USA.
The notion of "half fire, half ice" was recently introduced to describe an exotic macroscopic ground-state degeneracy emerging in a ferrimagnet under the critical magnetic field, in which the "hot" spins are fully disordered on the sublattice with smaller magnetic moments and the "cold" spins are fully ordered on the sublattice with larger magnetic moments. Here, we further point out that this state has a twin named "half ice, half fire" in which the hot and cold spins switch positions. The new state is an excited state-thus hidden in the ground-state phase diagram-and is robust with respect to the interactions that destroy the half-fire, half-ice state.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!