Double-peak Structure Research Articles

Probing the neutrino seesaw scale with gravitational waves

Neutrinos are the most elusive particles of the Standard Model. The physics behind their masses remains unknown and requires introducing new particles and interactions. An elegant solution to this problem is provided by the seesaw mechanism. Typically considered at a high scale, it is potentially testable in gravitational wave experiments by searching for a spectrum from cosmic strings, which offers a rather generic signature across many high-scale seesaw models. Here we consider the possibility of a low-scale seesaw mechanism at the PeV scale, generating neutrino masses within the framework of a model with gauged U(1) lepton number. In this case, the gravitational wave signal at high frequencies arises from a first order phase transition in the early Universe, whereas at low frequencies it is generated by domain wall annihilation, leading to a double-peaked structure in the gravitational wave spectrum. The signals discussed here can be searched for in upcoming experiments, including gravitational wave interferometers, pulsar timing arrays, and astrometry observations. Published by the American Physical Society 2024

Toroidal torques due to n=1 magnetic perturbations in ITER baseline scenario

Abstract Toroidal torques, generated by the resonant magnetic perturbation (RMP) and acting on the plasma column, are numerically systematically investigated for an ITER baseline scenario. The neoclassical toroidal viscosity (NTV), in particular the resonant portion, is found to provide the dominant contribution to the total toroidal torque under the slow plasma flow regime in ITER. While the electromagnetic torque always opposes the plasma flow, the toroidal torque associated with the Reynolds stress enhances the plasma flow independent of the flow direction. A peculiar double-peak structure for the net NTV torque is robustly computed for ITER, as the toroidal rotation frequency is scanned near the zero value. This structure is found to be ultimately due to a non-monotonic behavior of the wave-particle resonance integral (over the particle pitch angle) in the superbanana plateau NTV regime in ITER. These findings are qualitatively insensitive to variations of a range of factors including the wall resistivity, the plasma pedestal flow and the assumed frequency of the rotating RMP field.

Lyα Profile Shape as an Escape-fraction Diagnostic at High Redshift

While the shape of the Lyα profile is viewed as one of the best tracers of ionizing-photon escape fraction (f esc) within low-redshift (z ∼ 0.3) surveys of the Lyman continuum, this connection remains untested at high redshift. Here, we combine deep, rest-UV Keck/LRIS spectra of 80 objects from the Keck Lyman Continuum Spectroscopic Survey with rest-optical Keck/MOSFIRE spectroscopy in order to examine potential correlations between Lyα profile shape and the escape of ionizing radiation within z ∼ 3 star-forming galaxies. We measure the velocity separation between double-peaked Lyα emission structure (v sep), between red-side Lyα emission peaks and systemic (v Lyα,red), and between red-side emission peaks and low-ionization interstellar absorption lines (v Lyα−LIS). We find that the IGM-corrected ratio of ionizing to nonionizing flux density is significantly higher in KLCS objects with lower v Lyα,red. We find no significant trend between measures of ionizing-photon escape and v Lyα−LIS. We compare our results to measurements of z ∼ 0.3 “Green Peas” from the literature and find that KLCS objects have larger v sep at fixed v Lyα,red, larger f esc at fixed v Lyα,red, and higher v Lyα,red overall than z ∼ 0.3 analogs. We conclude that the Lyα profile shapes of our high-redshift sources are fundamentally different, and that measurements of profile shape such as v Lyα,red map on to f esc in different ways. We caution against building reionization-era f esc diagnostics based purely on Lyα profiles of low-redshift dwarf galaxies. Tracing v sep, v Lyα,red, and f esc in a larger sample of z ∼ 3 galaxies will reveal how these variables may be connected for galaxies at the epoch of reionization.

Nernst effect of the dice lattice in a strong magnetic field

The dice lattice bears a similar honeycomb lattice structure to graphene but with a non-dispersive flat band intersecting the Dirac bands at the band center. In this work, we investigate Nernst effect of the dice lattice in a strong magnetic field, focusing on the role of the flat band. By using the Chebyshev polynomial Green’s function method, we show that no Nernst effect (Sxy=0) is around the Dirac point in the clean limit contrary to the graphene case because of the existence of a zero Hall conductivity platform. However, an unconventional negative Sxy of the double-peak structure emerges instead when the flat band is broadened by disorder and temperature. In addition, when a mass term of Dirac electrons is introduced in the system to open an energy gap, a negative single peak of Sxy appears at the Dirac point and this is due to the derivative quantum Hall effect of non-Dirac electrons in the flat band appearing in the energy gap.

Ion heating/transport characteristics of the merging startup plasma scenario in the TS-6 spherical tokamak

Here we report the ion heating/transport characteristics of the merging startup scenario in the TS-6 spherical tokamak. In addition to the previously investigated impulsive heating process during magnetic reconnection, here we also focus on a longer time scale response of the ion temperature profile both during and after merging, including the semi-steady plasma confinement phase. During magnetic reconnection, (i) the ion temperature profile forms a poloidally asymmetric profile around the X-point in the initiation phase and (ii) radially asymmetric higher deposition is obtained at the high field side. After merging, (iii) the radially asymmetric double-peak structure is affected by parallel heat conduction and is aligned with field lines, but it does not simply become a flux function on a microsecond time scale—inboard/outboard asymmetry lasts even in the semi-steady confinement phase. (iv) Under the influence of the low-aspect-ratio configuration, there is a two to three times higher toroidal field on the high-field side on the same closed flux surface: characteristic asymmetry of inboard/outboard ion temperature has been found experimentally for the first time.

Hemispheric analysis of the magnetic flux in regular and irregular solar active regions

ABSTRACT Studying the hemispheric distribution of active regions (ARs) with different magnetic morphologies may clarify the features of the dynamo process that is hidden under the photospheric level. The magnetic flux data for 3047 ARs from the CrAO catalogue (https://sun.crao.ru/databases/catalog-mmc-ars), between May 1996 and December 2021 (cycles 23 and 24) were used to study ARs cyclic variations and perform correlation analysis. According to the magneto-morphological classification (MMC) of ARs proposed earlier, subsets of the regular (obeying empirical rules for sunspots) and irregular (violating these rules) ARs were considered separately. Our analysis shows the following: For ARs of each MMC type, in each of the hemispheres, time profiles demonstrate a multipeak structure. The double-peak structure of a cycle is formed by ARs of both MMC types in both hemispheres. For the irregular ARs, the pronounced peaks occur in the second maxima (close to the polar field reversal). Their significant hemispheric imbalance might be caused by a weakening of the toroidal field in one of the hemispheres due to the interaction between the dipolar and quadrupolar components of the global field, which facilitates the manifestation of the turbulent component of the dynamo. The similarity of the irregular ARs activity that was found in adjacent cycles in different hemispheres also hints at realization of the mix-parity dynamo solution. For the quadrupolar-like component of the flux (compiled in the simple axisymmetric approximation), signs of oscillations with a period of about 15 years are found, and they are pronounced specifically for the irregular groups. This MMC type ARs might also contribute in $\alpha$-quenching.

The 4.2 ka event: A review of palaeoclimate literature and directions for future research

In recent years, much evidence has been presented on the 4.2 ka event. A review of 317 palaeoclimate papers shows that dry conditions were common during the event, especially from Eastern Mediterranean to India. The 4.2 ka event was not, however, a global drought event. Wet conditions were reported especially for central/northern Europe and sub-Saharan Africa. The 4.2 ka event is typically characterized either as short (4.2–4.0 ka) or long (4.4–3.8 ka) episode, possibly developing over an extended interval of time, in keeping with the North Atlantic forcing and correlating with the Bond 3 event of ice-rafted debris. This forcing is understood to drive a southward migration of the Inter-Tropical Convergence Zone (ITCZ), resulting in decreased rainfall over most of the Asian monsoon region, with possibility that an interplay of El Niño–Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO) has modulated the global circulation. Cold conditions were also reported but less frequently, in comparison to other Bond events such as the 8.2 ka event, Dark Ages Cold Period and Little Ice Age. Some high-resolution records show a double peak structure of which two anomalies are tree-ring dated to 4.14–4.05 ka and 3.97 ka. Accurately and precisely dated high-resolution records indicative of various climatic variables, especially outside of the traditional study region (Mediterranean–Middle East–India–China), including reconstructions of the ENSO and NAO histories and ITCZ migrations, are crucially needed for rigorous examination of the global scale characteristics of the 4.2 ka event and its forcings. Such research seems to be just beginning.

Revisiting the abundance pattern and charge-exchange emission in the centre of M 82

Context. The interstellar medium (ISM) in starburst galaxies contains many chemical elements that are synthesised by core-collapse supernova explosions. By measuring the abundances of these metals, we can study the chemical enrichment within the galaxies and the transportation of metals into the circumgalactic environment through powerful outflows. Aims. We performed a spectral analysis of the X-ray emissions from the core of M 82 using the Reflection Grating Spectrometer (RGS) on board XMM-Newton to accurately estimate the metal abundances in the ISM. Methods. We analysed over 300 ks of RGS data observed with 14 position angles, covering a cross-dispersion width of 80 arcsec. We employed multi-temperature thermal plasma components in collisional ionisation equilibrium (CIE) to reproduce the observed spectra, each of which exhibited a different spatial broadening. Results. The O VII band CCD image shows a broader distribution that those for the O VIII and Fe-L bands. The O VIII line profiles have a prominent double-peaked structure that corresponds to the north- and southward outflows. The O VII triplet feature exhibits marginal peaks. A single CIE component that is convolved with the O VII band image approximately reproduces the spectral shape. A CIE model combined with a charge-exchange emission model also successfully reproduces the O VII line profiles. However, the ratio of these two components varies significantly with the observed position angles, which is physically implausible. Spectral fitting of the broadband spectra suggests a multi-temperature phase in the ISM that is approximated by three components at 0.1, 0.4, and 0.7 keV. Notably, the 0.1 keV component exhibits a broader distribution than the 0.4 and 0.7 keV plasmas. The derived abundance pattern shows super-solar N/O, solar Ne/O and Mg/O, and half-solar Fe/O ratios. These results indicate the chemical enrichment by core-collapse supernovae in starburst galaxies.

Insight–HXMT observations of thermonuclear X-ray bursts from 4U 1608–52 in the low/hard state: the energy-dependent hard X-ray deficit and cooling saturation of the corona

ABSTRACT During thermonuclear bursts, it is suspected that cooling of the corona by the burst emission may be the cause of hard X-ray deficits. Although such a deficit has been observed in nine sources, it has not been observed from 4U 1608–52, a nearby prolific burster. Therefore, the authenticity and universality of the hard X-ray deficit may be in question. To investigate this suspicion, Insight–HXMT performed cadence observations during the low/hard state of 4U 1608–52 in 2022 September and detected 10 thermonuclear X-ray bursts. Two of these bursts show a double-peaked structure in the soft X-ray band, which could be caused by the high temperature of the burst emission and a marginal photospheric radius expansion (PRE) around the burst peak time. This is indicated by their peak fluxes being up to the Eddington limit and having a large colour factor at the peak of the bursts. A hard X-ray deficit is observed at a significant level during bursts at > 30 keV. Furthermore, the fraction of this deficit shows saturation at 50 per cent for the first eight bursts. This saturation may indicate that the corona is layered and only part of the corona is cooled by the bursts: for example, the part close to the neutron star surface is cooled while the rest remains intact during bursts. This result provides a clue to the geometry of the corona. For example, a possible scenario is that the corona has two forms: a quasi-spheric corona between the neutron star and the disc and a disc corona on both surfaces of the disc.

Further prediction on the possible double-peak structure of the X17 particle

The [Formula: see text] particle, discovered by [A. J. Krasznahorkay et al., Phys. Rev. Lett. 116, 042501 (2016), doi:10.1103/PhysRevLett.116.042501] at ATOMKI, was recently confirmed in the [Formula: see text] invariant mass spectra by [K. U. Abraamyan, C. Austin, M. I. Baznat, K. K. Gudima, M. A. Kozhin, S. G. Reznikov and A. S. Sorin, arXiv:2311.18632] at JINR. We notice with surprise and interest that the [Formula: see text] seems to have a double-peak structure. This is in a possible coincidence with our QCD sum rule study of [H.-X. Chen, arXiv:2006.01018], where we interpreted the [Formula: see text] as a tetraquark state composed of four bare quarks ([Formula: see text]), and claimed that “A unique feature of this tetraquark assignment is that we predict two almost degenerate states with significantly different widths”. These two different tetraquark states are described by two different chiral tetraquark currents [Formula: see text] and [Formula: see text]. To verify whether the tetraquark assignment is correct or not, we replace the up and down quarks by the strange quarks, and apply the QCD sum rule method to study the other four chiral tetraquark currents [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]. We calculate their correlation functions, and find that non-perturbative QCD effects do not contribute much to them. Our results suggest that there may exist four almost degenerate tetraquark states with masses about [Formula: see text] MeV. Each of these states is composed of four bare quarks, either [Formula: see text] or [Formula: see text].

Dramatic Rebrightening of the Type-changing Stripped-envelope Supernova SN 2023aew

Multipeaked supernovae with precursors, dramatic light-curve rebrightenings, and spectral transformation are rare, but are being discovered in increasing numbers by modern night-sky transient surveys like the Zwicky Transient Facility. Here, we present the observations and analysis of SN 2023aew, which showed a dramatic increase in brightness following an initial luminous (−17.4 mag) and long (∼100 days) unusual first peak (possibly precursor). SN 2023aew was classified as a Type IIb supernova during the first peak but changed its type to resemble a stripped-envelope supernova (SESN) after the marked rebrightening. We present comparisons of SN 2023aew’s spectral evolution with SESN subtypes and argue that it is similar to SNe Ibc during its main peak. P-Cygni Balmer lines are present during the first peak, but vanish during the second peak’s photospheric phase, before Hα resurfaces again during the nebular phase. The nebular lines ([O i], [Ca ii], Mg i], Hα) exhibit a double-peaked structure that hints toward a clumpy or nonspherical ejecta. We analyze the second peak in the light curve of SN 2023aew and find it to be broader than that of normal SESNe as well as requiring a very high 56Ni mass to power the peak luminosity. We discuss the possible origins of SN 2023aew including an eruption scenario where a part of the envelope is ejected during the first peak and also powers the second peak of the light curve through interaction of the SN with the circumstellar medium.

Nonideal effects on ionization potential depression and ionization balance in dense Al and Au plasmas.

For low-density plasmas, the ionization balance can be properly described by the normal Saha equationin the chemical picture. For dense plasmas, however, nonideal effects due to the interactions between the electrons and ions and among the electrons themselves affect the ionization potential depression and the ionization balance. With the increasing of plasma density, the pressure ionization starts to play a more obvious role and competes with the thermal ionization. Based on a local-density temperature-dependent ion-sphere model, we develop a unified and self-consistent theoretical formalism to simultaneously investigate the ionization potential depression, the ionization balance, and the charge states distributions of the dense plasmas. In this work, we choose Al and Au plasmas as examples as Al is a prototype light element and Au is an important heavy element in many research fields such as in the inertial confinement fusion. The nonideal effect of the free electrons in the plasmas is considered by the single-electron effective potential contributed by both the bound electrons of different charge states and the free electrons in the plasmas. For the Al plasmas, we can reconcile the results of two experiments on measuring the ionization potential depression, in which one experiment can be better explained by the Stewart-Pyatt model while the other fits better with the Ecker-Kröll model. For dense Au plasmas, the results show that the double peak structure of the charge state distribution appears to be a common phenomenon. In particular, the calculated ionization balance shows that the two- and three-peak structures can appear simultaneously for denser Au plasmas above ∼30g/cm^{3}.

Spin-resolved counting statistics as a sensitive probe of spin correlation in transport through a quantum dot spin valve

We investigate the noise in spin transport through a single quantum dot (QD) tunnel coupled to ferromagnetic (FM) electrodes with noncollinear magnetizations. Based on a spin-resolved quantum master equation, auto- and cross-correlations of spin-resolved currents are analyzed to reveal the underlying spin transport dynamics and characteristics for various polarizations. We find the currents of majority and minority spins could be strongly autocorrelated despite uncorrelated charge transfer. The interplay between tunnel coupling and the Coulomb interaction gives rise to an exchange magnetic field, leading to the precession of the accumulated spin in the QD. It strongly suppresses the bunching of spin tunneling events and results in a unique double-peak structure in the noise of the net spin current. The spin autocorrelation is found to be susceptible to magnetization alignments, which may serve as a sensitive tool to measure the magnetization directions between the FM electrodes.

The double-peaked type I X-ray bursts with different mass accretion rate and fuel composition

ABSTRACT Using the mesa (Modules for Experiments in Stellar Astrophysics) code, we have carried out a detailed survey of the available parameter space for the double-peaked type I X-ray bursts. We find that the double-peaked structure appears at mass accretion rate $\dot{M}$ in the range of $\sim (4-8)\times 10^{-10}\, {\rm M}_{\odot }\,{\rm yr}^{-1}$ when metallicity Z = 0.01, while in the range of $\sim (4-8)\times 10^{-9}\, {\rm M}_{\odot }\,\rm {yr}^{-1}$ when Z = 0.05. Calculations of the metallicity impact suggest that the double peaks will disappear when Z ≲ 0.005 for $\dot{M}=5\times 10^{-10}\, {\rm M}_{\odot }\,\rm {yr}^{-1}$ and Z ≲ 0.04 for $\dot{M}=5\times 10^{-9}\, {\rm M}_{\odot }\,\rm {yr}^{-1}$. Besides, the impacts of base heating Qb, as well as nuclear reaction waiting points: $^{22}\rm {Mg}$, $^{26}\rm {Si}$, $^{30}\rm {S}$, $^{34}\rm {Ar}$, 56Ni, $^{60}\rm Zn$, $^{64}\rm {Ge}$, $^{68}\rm {Se}$, and $^{72}\rm {Kr}$ have been explored. The luminosity of the two peaks decreases as Qb increases. 68Se(p, γ)69Br is the most sensitive reaction, the double peaks disappear assuming that 56Ni(p, γ)57Cu, and 64Ge(p, γ)65As reaction rates have been underestimated by a factor of 100 and the 22Mg(α, p)25Al reaction rate has been overestimated by a factor of 100, which indicates that 22Mg, 56Ni, 64Ge, and 68Se are possibly the most important nuclear waiting points impedance in the thermonuclear reaction flow to explain the double-peaked bursts. Comparisons to the double-peaked bursts from 4U 1636−53 and 4U 1730−22 suggest that the nuclear origins of double-peaked type I X-ray bursts are difficult to explain the observed larger peak times ($t_{\rm p,1}\gtrsim 4\, {\rm s}$, $t_{\rm p,2}\gtrsim 8\, {\rm s}$) and smaller peak ratio (r1, 2 ≲ 0.5). The composition of ashes from double-peaked bursts is very different from the single-peaked bursts especially for the heavier p-nuclei.

Identifying reliable periods in 2MASS J09213414–5939068, IGR J16167–4957, and V667 Pup

Detailed timing analyses of three cataclysmic variables, namely 2MASS J09213414−5939068, IGR J16167−4957, and V667 Pup are carried out using the long-baseline and high-cadence optical photometric data from the Transiting Exoplanet Survey Satellite (TESS). Periods of 908.12 ± 0.05 s and 990.10 ± 0.06 s are observed in the optical variation of 2MASS J09213414−5939068 that were not found in earlier studies and appear to be probable spin and beat periods of the system, respectively. The presence of multiple periods at spin, beat, and other sidebands indicates that 2MASS J09213414−5939068 likely belongs to an intermediate polar class of magnetic cataclysmic variables that seems to be accreted via a disc-overflow mechanism. Clear evidence of a period of 582.45 ± 0.04 s is found during the TESS observations of IGR J16167−4957, which can be interpreted as the spin period of the system. Strong modulation at this frequency supports its classification as an intermediate polar, where accretion may primarily be governed by a disc. The dominance of the spin pulse unveils the disc-fed dominance accretion in V667 Pup, but the detection of the previously unknown beat period of 525.77 ± 0.03 s suggests that a portion of the material is also accreted through a stream. Moreover, the double-peaked structure observed in the optical spin pulse profile of V667 Pup suggests the possibility of a two-pole accretion geometry, where each pole accretes at a different rate and is separated by 180°.

A study of extreme C iii]1908 & [O iii]88/[C ii]157 emission in Pox 186: Implications for JWST+ALMA (FUV+FIR) studies of distant galaxies

Abstract Carbon spectral features are ubiquitous in the ultraviolet (UV) and far-infrared (FIR) spectra of the reionization-era galaxies. We probe the ionized carbon content of a dwarf galaxy Pox 186 using the UV, optical, mid-infrared and FIR data taken with Hubble, Gemini, Spitzer and Herschel, respectively. This local (z∼0.0040705) galaxy is likely an analogue of reionization-era galaxies, as revealed by its extreme FIR emission line ratio, [O iii] 88μm/[C ii] 157μm (>10). The UV spectra reveal extreme C iii] λλ 1907, 1909 emission with the strongest equivalent width (EW) = 35.85 ± 0.73 Å detected so far in the local (z∼0) Universe, a relatively strong C iv λλ 1548, 1550 emission with EW = 7.95 ±0.45 Å, but no He ii λ 1640 detection. Several scenarios are explored to explain the high EW of carbon lines, including high effective temperature, high carbon-to-oxygen ratio, slope and upper mass of top-heavy initial mass function, hard ionizing radiation and in-homogeneous dust distribution. Both C iii] and C iv line profiles are broadened with respect to the O iii] λ 1660 emission line. Each emission line of C iv λλ 1548, 1550 shows the most distinct double-peak structure ever detected, which we model via two scenarios, firstly a double-peaked profile that might emerge from resonant scattering and secondly, a single nebular emission line along with a weaker interstellar absorption. The study demonstrates that galaxies with extreme FIR properties may also show extreme UV properties, hence paving a promising avenue of using FIR+UV in the local (via Hubble+Herschel/SOFIA) and distant (via JWST+ALMA) Universe for unveiling the mysteries of the reionization-era.

Hole-states in Li doped NiO: doping dependence of Zhang-Rice spectral weight.

We report on structural evolution and a dynamical transfer of spectral weight as observed in O K-edge X-ray absorption (XA) spectra upon hole doping in LixNi1-xO (0 ≤ x ≤ 0.24). We find that the unit cell of doped NiO evolves in a specific way up to an intermediate doping level (x = 0.12) and then follows a different trend. A double peak structure (one is localized and the other is more delocalized) of low energy spectral weight (LESW) at the O K-edge is identified and quantified. Normalized LESW is found to increase linearly with an effective doping concentration (∼x/(1 - 2x)) with a change in slope at x = 0.12, which is correlated to the observed structural evolution. Doping dependence of Ni L3-edge XA spectral shape closely follows the localized peak of LESW at the O K-edge. Our observations strongly support the Zhang-Rice (ZR) picture, confirming that doped holes in NiO are of primarily ZR character. Furthermore, we find that Fe co-doping destroys the ZR spectral weight and recovers the spectral shapes to that of NiO.

Research on magnetic memory inspection signal characteristics of multi-parameter coupling pipeline welds

Magnetic memory inspection technology is an effective method for detecting early damage in ferromagnetic materials. However, the commonly used force-magnetic coupling models are insufficient for analyzing the distribution characteristics of magnetic signals in ferromagnetic material welds. This study first analyzes the influence of metal phase transformation and residual stress on the magnetic hysteresis characteristics of materials. Based on the principle of magnetic hysteresis characteristics, the magnetic charge density under the combined action of stress and phase transformation is determined, and a magnetic memory analysis model is established for multi-parameter coupling. The study quantitatively calculates the effects of phase transformation volume fraction, residual stress, the lift-off effect, and cracks on the magnetic signal features at welds. The research results show that the magnetic memory signals at welds exhibit extreme values in the tangential component and sinusoidal fluctuations with zero-crossings in the normal component. The peak-to-peak values of both the normal and tangential components of the magnetic signal increase with an increase in metal phase transformation and residual stress, while they decrease with the increase of the lift-off effect. When cracks appear in the weld, the normal component exhibits a double-peak and valley structure, with the inner side representing crack features and the outer side representing weld features. The tangential component shows a maximum value at the center of the crack. Based on the peak and valley values of the magnetic signal, a damage grade index F is determined. The damage index F can characterize the level of weld damage, decreasing approximately linearly with increasing stress.

Dispersive wave manipulation by the spectral Heaviside step phase modulation

We investigate the dispersive waves (DWs) emitted from shaped pulses with spectral Heaviside step phases (HSPs). The spectrally HSP-modulated pulse exhibits a unique double-peak structure, where the intensity and separation of the twin peaks are determined by the modulation depth and frequency detuning. By tailoring the parameters of the HSP suitably, we can control the DW emission with regard to resonant frequency and conversion efficiency. As the intensity ratio or relative separation of neighboring peaks is elaborately chosen, the DW emission can be effectively boosted, or a solitonic cage can be constructed for realizing temporal reflections and refractions associated with spectral broadening and multi-peak spectra of the output DWs. These findings offer a straightforward and efficient approach for controlling the DW emission, which is highly relevant to the advancement of supercontinuum generation and wavelength conversion technology.

Unveiling the double-peak structure of quantum oscillations in the specific heat

Quantum oscillation phenomenon is an essential tool to understand the electronic structure of quantum matter. Here we report a systematic study of quantum oscillations in the electronic specific heat Cel in natural graphite. We show that the crossing of a single spin Landau level and the Fermi energy give rise to a double-peak structure, in striking contrast to the single peak expected from Lifshitz-Kosevich theory. Intriguingly, the double-peak structure is predicted by the kernel term for Cel/T in the free electron theory. The Cel/T represents a spectroscopic tuning fork of width 4.8kBT which can be tuned at will to resonance. Using a coincidence method, the double-peak structure can be used to accurately determine the Landé g-factors of quantum materials. More generally, the tuning fork can be used to reveal any peak in fermionic density of states tuned by magnetic field, such as Lifshitz transition in heavy-fermion compounds.