Scanning Hall probe imaging of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi>ErNi</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">B</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:math>

Bluhm, Hendrik; Sebastian, Suchitra E.; Guikema, Janice Wynn; Fisher, I. R.; Moler, Kathryn A.

doi:10.1103/physrevb.73.014514

Cited by 34 publications

(40 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On cooling down from just above T N the α a initially increases and then goes into sharp, deep minimum. Such behavior (as opposed to some sort of λ-like anomaly) may be associated with possible formation of the antiferromagnetic domains (twins) in the crystal in zero or small fields [22,23] due to orthorhombic structural distortion below T N [14]. The complexity of in-plane thermal expansion of ErNi 2 B 2 C near T N is illustrated in Fig.…”

mentioning

confidence: 99%

Anisotropic thermal expansion and evaluation of uniaxial pressure dependence of superconducting and magnetic transitions in ErNi2B2C

Bud’ko¹,

Schmiedeshoff²,

Canfield³

2006

Solid State Communications

View full text Add to dashboard Cite

We present anisotropic thermal expansion measurements on single crystalline ErNi 2 B 2 C. All three, superconducting, antiferromagnetic and weak ferromagnetic phase transitions are unambiguously distinguished in the data. Anisotropic uniaxial pressure dependencies of the transitions are estimated based on the Ehrenfest relation, leading to a conclusion, in particular, that weak ferromagnetic state will be suppressed by small, order of several kbar, hydrostatic pressure.Key words: A. magnetically ordered materials, A. superconductors, D. thermal expansion PACS: 65.40. De, 74.70.Dd, 75.30.Kz, 75.40.Cx, 75.80.+q Quaternary borocarbides, in particular the members of the RNi 2 B 2 C (R = Gd-Lu, Y) series of compounds, exhibit a plethora of complex phenomena: co-existence of local moment magnetism and superconductivity, non-locality and flux line lattice transitions, heavy fermion physics and intricate metamagnetism [1,2,3,4]. ErNi 2 B 2 C superconducts below ∼ 10 K [5,6], below T N ≈ 6 K superconductivity coexists with an incommensurate antiferromagnetic state with the ordering wave vector q ≈ 0.55 a * [8,9,7], and then, on further cooling, a weak ferromagnetic component develops below T W F M ≈ 2.3 K [10,11,12].Despite a large number of publications on physical properties of ErNi 2 B 2 C, few of them address temperature dependent structural changes in the material. The evolution of the lattice parameters between 360 K and 90 K, as measured by single crystal X-ray diffraction, was reported in Ref. [13]. A magnetoelastic tetragonal-to-orthorhombic structural distortion was observed [14] below T N by synchrotron X-ray scattering. A λ-type anomaly in thermal expansion at In this publication we report high resolution, anisotropic (c-axis and a-axis) thermal expansion (TE) and longitudinal, low temperature, magnetostriction (MS) measurements for H a on single crystalline ErNi 2 B 2 C. These measurements were performed with the intent to study the anomalies in TE associated with all three salient transition temperatures (to the best of our knowledge, for two of them, T c and T W F M , no TE anomalies were reported so far) and to evaluate the uniaxial pressure derivatives of the three transition temperatures using the the thermodynamic Ehrenfest relation.Plate-like single crystals of ErNi 2 B 2 C with the c-axis perpendicular to the plates were grown by a Ni 2 B high temperature flux method (see Refs. [1,7,17,18] for more details). For the TE/MS measurements the ErNi 2 B 2 C crystal was shaped into a nearly rectangular bar, with two pairs of parallel surfaces, so that the measurements were performed along [100] (L = 2.23 mm) and [001] (L = 1.42 mm) directions. After shaping, the sample was annealed in dynamic vacuum (10 −5 − 10 −6 Torr) at 950• C for ∼ 100 hours [19]. Thermal expansion and magnetostriction were measured using a capacitive dilatometer constructed of OFHC copper; a detailed description of the dilatometer will appear elsewhere [20]. The dilatometer was mounted in a Quantum Design PPMS-14 instrumen...

show abstract

mentioning

confidence: 99%

Anisotropic thermal expansion and evaluation of uniaxial pressure dependence of superconducting and magnetic transitions in ErNi2B2C

Bud’ko¹,

Schmiedeshoff²,

Canfield³

2006

Solid State Communications

View full text Add to dashboard Cite

show abstract

“…This indicates the presence of correlated defects (see e.g. [36,38]). It is possible that these are the twin boundaries one expects because at x=0.26 C T is below the structural phase transition (50 K at x=0.26 [5,9,20]).…”

mentioning

confidence: 99%

Local characterization of superconductivity inBaFe2(As1−xPx)<

et al. 2015

View full text Add to dashboard Cite

We use magnetic force microscopy (MFM) to characterize superconductivity across the superconducting dome in BaFe 2 (As 1-x P x ) 2 , a pnictide with a peak in the penetration depth ( ab λ )at optimal doping (x opt ), as shown in sample-wide measurements. Our local measurements show a peak at x opt and a C T vs.2 ab λ − dependence similar on both sides of x opt . Near the underdoped edge of the dome ab λ increases sharply suggesting that superconductivity competes with another phase. Indeed MFM vortex imaging shows correlated defects parallel to twin boundaries only in underdoped samples and not for x ≥ x opt .2The origin of superconductivity in the iron-based materials is still under debate although there is mounting evidence for the role of magnetic order and fluctuations [1][2][3][4]. For instance, it is well established that the parent compound for the pnictides is a metal with spin-density-wave (SDW) order and that doping by electrons, holes or isovalently gives rise to superconductivity and suppresses the magnetic order and an associated structural phase transition [5][6][7][8][9]. Moreover, the optimal doping for the superconducting transition temperature ( C T ) is only slightly higher than the maximum doping for which SDW order has been observed. Here we report magnetic force microscopy (MFM) measurements of the local absolute value of the in-plane penetration depth ( ab λ ) in BaFe 2 (As 1-x P x ) 2 . At the location where we measure ab λ we also measure the local C T in order to determine the relationship between these two fundamental superconducting properties. In addition we use MFM to map the location of superconducting vortices, which can become trapped by defects in the material. This allows us to learn about correlated defects that may arise as a result of structural and magnetic phase transitions.Our samples were high-quality single crystals grown by the self-flux method and annealed in affected by a region in the sample only up to a few micrometers in diameter and only a few hundred nanometers deep, on the order of ab λ , our results are less sensitive to inhomogeneity than measurements which average over the whole sample [28,29]. The locality also allows us to check homogeneity by comparing measurements from different areas in each sample.In our setup the magnetic MFM tip [30] is subjected to forces due to the Meissner response from the superconducting sample, the magnetic field from vortices and magnetic fields from other sources, if they are present. We minimize the electrostatic forces between the tip and the sample by compensating for the contact potential difference. We work with frequency modulated MFM in which the forces on the tip shift the resonant frequency of the cantilever holding it:is the cantilever's natural resonance frequency, 0 k is the spring constant, z is the direction normal to the sample surface and C is a constant offset) [31].For ab λ measurements we cool the sample in low magnetic field and find an area without vortices and visible defects. For this we scan...

show abstract

“…Until recently, low temperatures of superconducting and magnetic phase transitions of known single crystals, as well as the requirement of a high spatial resolution, have limited experimental capabilities for visualization of the magnetic flux structure employing e.g. magnetic force microscopy (MFM), 19 scanning Hall probe imaging, 20 and decoration with magnetic nanoparticles.…”

mentioning

confidence: 99%

Visualization of the magnetic flux structure in phosphorus-doped EuFe2As2 single crystals

et al. 2017

View full text Add to dashboard Cite

Magnetic flux structure on the surface of EuFe2(As1−xPx)2 single crystals with nearly optimal phosphorus doping levels x = 0.20, and x = 0.21 is studied by low-temperature magnetic force microscopy and decoration with ferromagnetic nanoparticles. The studies are performed in a broad temperature range. It is shown that the single crystal with x = 0.21 in the temperature range between the critical temperatures TSC = 22 K and TC = 17.7 K of the superconducting and ferromagnetic phase transitions, respectively has the vortex structure of a frozen magnetic flux, typical for type-II superconductors. The magnetic domain structure is observed in the superconducting state below TC. The nature of this structure is discussed.

show abstract

Scanning Hall probe imaging ofErNi2B2C

Cited by 34 publications

References 22 publications

Anisotropic thermal expansion and evaluation of uniaxial pressure dependence of superconducting and magnetic transitions in ErNi2B2C

Anisotropic thermal expansion and evaluation of uniaxial pressure dependence of superconducting and magnetic transitions in ErNi2B2C

Local characterization of superconductivity inBaFe2(As1−xPx)<

Visualization of the magnetic flux structure in phosphorus-doped EuFe2As2 single crystals

Contact Info

Product

Resources

About