Cryogenic Regime Research Articles

Temperature-dependent near-surface interstitial segregation in niobium

Niobium’s superconducting properties are affected by the presence and precipitation of impurities in the near-surface region. A systematic wide-temperature range x-ray diffraction study is presented addressing the effect of low temperatures (108 K–130 K) and annealing treatments (523 K in nitrogen atmosphere, 400 K in UHV) on the near-surface region of a hydrogen-loaded Nb(100) single-crystal. Under these conditions, the response of the natural surface oxides (Nb2O5, NbO2, and NbO) and the changes in the subsurface concentration of interstitial species in Nb are explored, thereby including the cryogenic temperature regime relevant for device operation. The formation and suppression of niobium hydrides in such conditions are also investigated. These treatments are shown to result in: (i) an increase in the concentration of interstitial species (oxygen and nitrogen) occupying the octahedral sites of the Nb bcc lattice at room temperature, both in the near-surface region and in the bulk. (ii) A decrease in the concentration of interstitials within the first 10 nm from the surface at 130 K. (iii) Hydride formation suppression at temperatures as low as 130 K. These results show that mild annealing in nitrogen atmosphere can suppress the formation of superconducting-detrimental niobium hydrides, while subsurface interstitial atoms tend to segregate towards the surface at 130 K, therefore altering the local concentration of impurities within the RF penetration depth of Nb. These processes are discussed in the context of the improvement of niobium superconducting radio-frequency cavities for next-generation particle accelerators.

Cryogenic Second-Harmonic Generation in Periodically Poled Lithium Niobate Waveguides

We demonstrate second-harmonic generation in a fiber-coupled periodically poled titanium in-diffused lithium niobate waveguide over the temperatures range from 292 to 4.4 K. We observe a reproducible shift in the phase-matched pump wavelength within the telecom band, which is at odds with the phase matching arising from existing models of the refractive indices in this temperature regime. We further investigate transient discontinuities while temperature cycling, which we attribute to the build-up and discharge of pyroelectric fields. Our results show that modifications of the Sellmeier coefficients for lithium niobate are required in the cryogenic temperature regime for our waveguides, but also establish titanium in-diffused waveguides in lithium niobate as a versatile nonlinear photonic integration platform compatible with cryogenic quantum technologies.

Transition in wear behavior and mechanical properties of novel high nitrogen martensitic steel in cryogenic temperature regimes

In space engines with liquid cryogenic LH2/ LO2 propellants, bearings are used in cryopumps subjected to harsh working conditions. High nitrogen martensitic stainless (HNMS) steel is a newly developed steel modifying currently used AISI 440C steel by partial substitution of C with N and is a potential replacement for AISI 440C as an antifriction bearing material In the present study, HNMS samples are austenitized at 1075 °C followed by cooling to −80 °C (CT) and then double tempering at 500 °C followed by cryogenic treatment at −196 °C for 8 h and 1 h soft tempering at 100 °C (CTC). Hardness increment by 7.9% and 7.6%, wear rate decrement by 11.11% and 7.69% and shift in DBTT from − 60 °C to − 90 °C was observed for CTC samples compared to CT samples at −196 °C and RT respectively. The improved properties for CTC samples might be due to precipitation and uniform distribution of tertiary nano precipitates.

Compliant polymer origami bellows in cryogenics

Mechanical applications for polymers at cryogenic temperatures are extremely limited due to decreased atomic mobility and ductility, resulting from glass transitions above the cryogenic regime (<120 K). As such, polymeric materials are known for cracking and low fatigue life. Crumpling polymer films has been historically researched as a mechanism to bypass this brittleness for mechanical actuation, but characterization of the fatigue life of polymer films to cyclical crumpling at 77 K determined that films shatter after a few cycles. To improve upon this performance, we fabricated thin-film origami bellows with Yoshimura and Kresling geometries to primarily restrict strain to below the elastic limit. We found the resulting bellows survived 100 full compression and extension cycles at 77 K by submerging the bellows in liquid nitrogen during testing: no tears or pinholes were detected in the bellows following a dye penetrant procedure. These results indicate that restricting the strain modes in thin-film polymers via origami structures could be applicable to a range of cryogenic technologies useful for liquid storage bladders, expandable seals, positive displacement fluid pumps, and flexible electronics.

Thin-Film Lateral SOI PIN Diodes for Thermal Sensing Reaching the Cryogenic Regime

This paper presents the performance of lateral SOI PIN diodes for temperature sensing in the range of 100 K to 400 K. Experimental results indicate that PIN diodes can be used to implement temperature sensors with high accuracy in cryogenic regime, provided that a suitable temperature range is chosen for calibration. Numerical simulations using Atlas two-dimensional simulator were performed in order to confirm this hypothesis and extend the analysis, verifying the accuracy of the existing model.

1/f Noise Reduction in Cryogenic Highly Compensated Silicon Thermistors

The thermal sensitivity and Low Frequency Noise (LFN) of compensation doped Silicon-On-Insulator (SOI) resistors are studied experimentally, down to the cryogenic regime. A high compensation nominal ratio K = N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</sub> /N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> of 0.82 is compared with uncompensated and partially compensated configurations, using Phosphorus and Boron as dopant species. The Temperature Coefficient of Resistance (TCR) reaches -2.7%/K at 80 K, for an effective compensation ratio close to 0.98 considering incomplete dopant ionization. The measurements reveal a low LFN with a nearly frequency-independent spectrum, far from the classical 1/f trend observed in uncompensated silicon. The mean value of the Hooge constant on the highly compensated silicon sample equals 3.15 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> at 300 K and 4.50 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> at 80 K. The normalized LFN at 80 K does not depend on the resistor length and thereby seems independent of the volume. Such high performance thermistors represent an attractive, mature and affordable solution for high performance thermal sensing.

Validation of Puck\u2019s failure criterion for CFRP composites in the cryogenic regime

For future launch vehicles, lightweight cryogenic pressure vessels are required for storage of the liquid hydrogen fuel. For their structural assessment, reliable and validated failure criteria are required. The present contribution provides an overview over the results of an ongoing research activity concerned with the validation of Puck’s composite failure criterion in the cryogenic regime. In a first step, an experimental investigation on unidirectionally fiber reinforced materials on coupon level has been performed. This test campaign has been complemented by tests on small breadboard-type specimens with an angle-ply stacking sequence. The specimens were featuring holes and tapered sections to provide stress gradients and concentrations. Test were performed at ambient temperature and in a liquid Helium environment. Puck’s failure criterion has been applied and found to provide a good prediction of first ply failure in both environments.

Microstructure and Tribological Properties of Tool Steel AISI O2 After Thorough Cryogenic Heat Treatment

Steel AISI O2 (type 9G2) for a cold-working tool after different quenching, tempering, and cryogenic treatment regimes is studied. It is established that after cryogenic treatment the amount of residual austenite decreases by a factor of 4.3 compared with a quenched condition. The highest hardness 69 HRC is achieved after quenching and cryogenic treatment, and in this case wear resistance is higher by a factor of 2.36 than after quenching and tempering. After cryogenic treatment there is also a reduction in friction coefficient.

Fast and Anomalous Exciton Diffusion in Two-Dimensional Hybrid Perovskites.

Two-dimensional hybrid perovskites are currently in the spotlight of condensed matter and nanotechnology research due to their intriguing optoelectronic and vibrational properties with emerging potential for light-harvesting and light-emitting applications. While it is known that these natural quantum wells host tightly bound excitons, the mobilities of these fundamental optical excitations at the heart of the optoelectronic applications are barely explored. Here, we directly monitor the diffusion of excitons through ultrafast emission microscopy from liquid helium to room temperature in hBN-encapsulated two-dimensional hybrid perovskites. We find very fast diffusion with characteristic hallmarks of free exciton propagation for all temperatures above 50 K. In the cryogenic regime, we observe nonlinear, anomalous behavior with an exceptionally rapid expansion of the exciton cloud followed by a very slow and even negative effective diffusion. We discuss our findings in view of efficient exciton-phonon coupling, highlighting two-dimensional hybrids as promising platforms for basic research and optoelectronic applications.

Cryogenic characterization of 180 nm CMOS technology at 100 mK

Conventional CMOS technology operated in cryogenic conditions has recently attracted interest for its use in low-noise electronics. We present one of the first characterizations of 180 nm CMOS technology at a temperature of 100 mK, extracting I/V characteristics, threshold voltages, and transconductance values, as well as observing their temperature dependence. We find that CMOS devices remain fully operational down to these temperatures, although we observe hysteresis effects in some devices. The measurements described in this paper can be used to inform the future design of CMOS devices intended to be operated in this deep cryogenic regime.

Thermometric SOI lateral diodes for bolometric application: Comparison between Schottky and p-i-n diodes

The thermometric behavior of lateral 50-nm thin Silicon-On-Insulator (SOI) diodes are studied down to 80 K, close to liquid-nitrogen temperature. A comparison between PtSi/n-Si Schottky and implanted p-i-n diodes is presented. In this study, the intrinsic region is a moderately-doped n-type region. Key figures are extracted at room and cryogenic temperatures for each diode. A Temperature Coefficient of Current (TCC) of 6 %/K at 298 K and for a bias current of 10 pA/µm is measured for both the Schottky Barrier Diode (SBD) and the p-i-n diode. Based on simulation results, both diode types should demonstrate an increase of the TCC in the cryogenic regime. However, experimentally, only the p-i-n configuration exhibits an increase with a TCC at 81.5 K reaching more than 15 %/K at low forward bias. Some arguments are presented to account for the discrepancy between simulation and experiment, especially in the case of the SBD. Suitability as thermometer for bolometric detection is discussed.

Scaling behavior of low-temperature orthorhombic domains in the prototypical high-temperature superconductor La1.875Ba0.125CuO4

Translational/rotational symmetry breaking and recovery in condensed matter systems are closely related to exotic physical properties such as superconductivity (SC), magnetism, spin density waves (SDW) and charge density waves (CDW). The interplay between different order parameters is intricate and often subject to intense debate, as in the case of CDW order and superconductivity. In La1:875Ba0:125CuO4 (LBCO), the locations of CDW domains are found to be pinned on the nanometer size scale. Coherent X-ray diffraction techniques open routes to directly visualize the domain structures associated with these symmetry changes. We have pushed Bragg Coherent Diffractive Imaging (BCDI) into the cryogenic regime where most phase transitions in quantum materials reside. Utilizing BCDI, we image the structural evolution of LBCO microcrystal samples during the high-temperature-tetragonal (HTT) to low-temperature-orthorhombic (LTO) phase transition. Our results show the formation of LTO domains close to the transition temperature and how the domain size varies with temperature. The LTO domain size is shown to decrease with temperature and to be inversely proportional to the magnitude of the orthorhombic distortion. The number of domains follows the secondary order parameter (or orthorhombic strain) measurement with a critical exponent that is consistent with the 3D universality class.

Er3+-to-Yb3+ and Pr3+-to-Yb3+ energy transfer for highly efficient near-infrared cryogenic optical temperature sensing.

Here, the very high thermal sensing capability of Er3+,Yb3+ doped LaF3 nanoparticles, where Er3+-to-Yb3+ energy transfer is used, is reported. Also Pr3+,Yb3+ doped LaF3 nanoparticles, with Pr3+-to-Yb3+ energy transfer, showed temperature sensing in the same temperature regime, but with lower performance. The investigated Er3+,Yb3+ doped LaF3 nanoparticles show a remarkably high relative sensitivity Sr of up to 6.6092% K-1 (at 15 K) in the near-infrared (NIR) region, in the cryogenic (15-105 K) temperature region opening a whole new thermometric system suitable for advanced applications in the very low temperature ranges. To date reports on NIR cryogenic sensors have been very scarce.

Evaluation of the mechanical performance of a composite multi-cell tank for cryogenic storage: Part II – Experimental assessment

This study focuses on the understanding of the thermal and structural behavior of an innovative Type IV multi-spherical composite-overwrapped pressure vessel through an experimental assessment that consists of hydrostatic testing at ambient conditions and pressure cycling with a cryogenic medium (LN2). During hydro-burst testing at a high displacement rate, the strain and damage progression is monitored with Digital-Image-Correlation (DIC) and Acoustic Emission (AE) techniques respectively. The effect of filling with LN2, pressure cycling and draining on the composite overwrap temperature gradient and strain evolution is additionally obtained with Fiber Bragg Gratings (FBGs) and thermocouples. Utilization of AE helped to reveal the different damage mechanisms occurring and enabled the evaluation of the pressure window of the multi-sphere. The experimental measurements in the cryogenic regime verified the suitability of the involved stiffness and coefficient of thermal expansion (CTE) fitting functions developed in [32] that enable to establish of a relationship between strain and temperature during cryogenic chill-down and pressure cycling. This study provides a framework about the suitability of conformal Type IV multi-spherical COPVs for cryogenic storage.

High resolution cryogenic transmission electron microscopy study of Escherichia coli Dps protein: First direct observation in quasinative state

Abstract The Dps protein of Escherichia coli is a homododecamer with an internal cavity accumulating iron oxides, transformed from ambient toxic Fe2+ into a harmless inorganic core. High resolution cryogenic transmission electron microscopy was applied to visualize the protein molecules and to characterize their ability to self-organization. Due to ultrafast freezing, the Dps dodecameric particles were observed as a “snapshot” of their natural state, and highly ordered two-dimensional layers with hexagonal symmetry were obtained. Thus, it became clear, that “super structured monolayers”, spanning over several thousand square nanometers can be formed under certain cryogenic regimes.

Low-temperature characteristics of normally-off AlGaN/GaN-on-Si gate-recessed MOSHFETs

We investigated the low-temperature operation of normally-off AlGaN/GaN heterostructure field-effect-transistors (HFETs) with gate-recessed metal-oxidesemiconductor (MOS) structure and normally-on Schottky-gate high-electron-mobility-transistors (HEMTs). Device characteristics measured from 100 to 300 K exhibited the distinct temperature-dependence between two types of devices. While the increase of on-current was observed from normally-on AlGaN/GaN Schottky-gate HEMTs due to the enhanced mobility in the two-dimensional electron gas (2-DEG) channel, normally-off AlGaN/GaN gate-recessed MOSHFETs demonstrated distinctive characteristics at 100 K including the decrease of on-current and the positive shift of threshold voltage (Vth). The temperature-dependence observed in gate-recessed MOSHFETs is attributed to the different characteristics of the recessed channel from the 2-DEG channel, in which the sheet carrier density (nsh) and mobility (μ) were reduced as the temperature approaches the cryogenic regime.

Complex temperature dependence of coupling and dissipation of cavity magnon polaritons from millikelvin to room temperature

Hybridized magnonic-photonic systems are key components for future information processing technologies such as storage, manipulation or conversion of data both in the classical (mostly at room temperature) and quantum (cryogenic) regime. In this work, we investigate a YIG sphere coupled strongly to a microwave cavity over the full temperature range from $290\,\mathrm{K}$ down to $30\,\mathrm{mK}$. The cavity-magnon polaritons are studied from the classical to the quantum regime where the thermal energy is less than one resonant microwave quanta, i.e. at temperatures below $1\,\mathrm{K}$. We compare the temperature dependence of the coupling strength $g_{\rm{eff}}(T)$, describing the strength of coherent energy exchange between spin ensemble and cavity photon, to the temperature behavior of the saturation magnetization evolution $M_{\rm{s}}(T)$ and find strong deviations at low temperatures. The temperature dependence of magnonic disspation is governed at intermediate temperatures by rare earth impurity scattering leading to a strong peak at $40\,$K. The linewidth $\kappa_{\rm{m}}$ decreases to $1.2\,$MHz at $30\,$mK, making this system suitable as a building block for quantum electrodynamics experiments. We achieve an electromagnonic cooperativity in excess of $20$ over the entire temperature range, with values beyond $100$ in the milliKelvin regime as well as at room temperature. With our measurements, spectroscopy on strongly coupled magnon-photon systems is demonstrated as versatile tool for spin material studies over large temperature ranges. Key parameters are provided in a single measurement, thus simplifying investigations significantly.

Thermal Cryogenic Regime of the Hydrosystem of Vilyui Hydroelectric Power Plants-1, 2: Geocryologic Monitoring

The dynamic behavior of the thermal-cryogenic regime of the hydrosystem of the Vilyui Hydroelectric Power Plant, which was the first to be constructed in a continuous space of permafrost rock, is presented. Features of the evolution of the thermal-moisture regime of the hydrosystem and the role of rockfill in thermal and mass transfer (crogenic) processes in the artificially created combined natural and engineered system are considered. It is established that, despite more than a 50-period of service, the thermal regime of the hydrosystem is in a fixed state and far from the steady state. Thawing of the shoreline abutments of the dam and in the reservoir floor is observed, and it is noted that the thermocryogenic processes seen in the lower rockfill retaining prism and at the base of the dam are both cyclic. The stability indicators of the hydrosystem are within the standards defined by Russian legislative documents.

Thermal considerations in the cryogenic regime for the BNL double ridge higher order mode waveguide

Brookhaven National Laboratory (BNL) has proposed to build an electron ion collider (EIC) as an upgrade to the existing Relativistic Heavy Ion Collider (RHIC). A part of the new design is to use superconducting radio frequency (SRF) cavities for acceleration, which sit in a bath of superfluid helium at a temperature of 2 K. SRF cavities designed for the BNL EIC create a standing electromagnetic wave, oscillating at a fundamental frequency of 647 MHz. Interaction of the charged particle beam with the EM field in the cavity creates higher order modes (HOM) of oscillation which have adverse effects on the beam when allowed to propagate down the beam tube. HOM waveguides are thus designed to remove this excess energy which is then damped at room temperature. As a result, these waveguides provide a direct thermal link between room temperature and the superconducting cavities adding a static thermal load. The EM wave propagating through the warmer sections of the waveguide creates an additional dynamic thermal load. This study calculates these thermal loads, concluding that the dynamic load is small in comparison to the static load. Temperature distributions are mapped on the waveguide and the number of heat intercepts required to efficiently manage thermal loads have been determined. In addition, a thermal radiation study has been performed and it is found that this contribution is around three orders of magnitude smaller than the static conduction and dynamic loads.

On the Physical Behavior of Cryogenic IV and III–V Schottky Barrier MOSFET Devices

The physical influence of temperature down to the cryogenic regime is analyzed in a comprehensive study and the comparison of IV and III-V Schottky barrier (SB) double-gate MOSFETs. The exploration is done using the Synopsys TCAD Sentaurus device simulator and first benchmarked with experimental data. The important device physics of both SB-MOSFETs and conventional MOSFETs are reviewed. The impact of temperature on device performance down to the liquid-nitrogen regime is then explored. We find reduced drive currents in SB-MOSFETs fabricated on small effective mass materials and that SB lowering can significantly improve SB-MOSFETs, especially at low temperatures.