Magnetic field splitting of the spin-resonance in CeCoIn5

Neutron scattering in strong magnetic fields is used to show the spin-resonance in superconducting CeCoIn5 (Tc=2.3 K) is a doublet. The underdamped resonance (\hbar \Gamma=0.069 \pm 0.019 meV) Zeeman splits into two modes at E_{\pm}=\hbar \Omega_{0}\pm g\mu_{B} \mu_{0}H with g=0.96 \pm 0.05. A linear extrapolation of the lower peak reaches zero energy at 11.2 \pm 0.5 T, near the critical field for the incommensurate "Q-phase" indicating that the Q-phase is a bose condensate of spin excitons.Comment: 5 pages, 4 figure

Fifth Graders’ Creativity in Inventions with and without Creative Articulation Instruction

Industry and authors of 21st Century Skill Frameworks are calling for student proficiency in creativity, problem-solving, innovation, collaboration, and communication skills. This project involved 13 fifth grade gifted students in inventing products for a specified audience with a set of given materials, time limit, and topic constraints. The complex, challenging project supports Next Generation Science Engineering Process Standard 3-5-ETS1-2 and applies concepts of plant and animal adaptations. The study had a counterbalanced, repeated measures design in which student made an initial invention during the pretest, then participated in two trials with one in the control condition and the other in the experimental condition. The experimental condition involved creative articulation strategies of considering the audience for the invention, effective communication of the ways the product meets audience needs, and peer collaboration and feedback to improve the product ideas. Students found the invention process initially very challenging, especially generating unique ideas. No statistically significant differences were found in product creativity or student attitudes, which were very positive, between the two conditions of the experiment, likely because of the small sample size. Analysis of student advertisements revealed a statistically significant difference favoring the experimental condition with a medium effect size for including reasons the product meets audience needs in the advertisement. Examples of student-made products and teacher analysis of selected products provide ideas for coaching students into higher creative skill levels. Additionally, statistically significant gains in creativity skill occurred from the pretest to the invention of the product during the first trial and this was maintained into the second trial with large effect size. This study showed that multiple invention opportunities allowed students to develop their skills better than a single activity. The challenging, complex activities helped students achieve a state of flow as they worked during the experiment and helped students develop their creativity

Quantum phase transitions and decoupling of magnetic sublattices in the quasi-two-dimensional Ising magnet Co3V2O8 in a transverse magnetic field

The application of a magnetic field transverse to the easy axis, Ising direction in the quasi-two-dimensional Kagome staircase magnet, Co3V2O8, induces three quantum phase transitions at low temperatures, ultimately producing a novel high field polarized state, with two distinct sublattices. New time-of-flight neutron scattering techniques, accompanied by large angular access, high magnetic field infrastructure allow the mapping of a sequence of ferromagnetic and incommensurate phases and their accompanying spin excitations. At least one of the transitions to incommensurate phases at \mu 0Hc1~6.25 T and \mu 0Hc2~7 T is discontinuous, while the final quantum critical point at \mu 0Hc3~13 T is continuous.Comment: 5 pages manuscript, 3 pages supplemental materia

Commensurate Fluctuations in the Pseudogap and Incommensurate spin-Peierls Phases of TiOCl

X-ray scattering measurements on single crystals of TiOCl reveal the presence of commensurate dimerization peaks within both the incommensurate spin-Peierls phase and the so-called pseudogap phase above T_c2. This scattering is relatively narrow in Q-space indicating long correlation lengths exceeding ~ 100 A below T* ~ 130 K. It is also slightly shifted in Q relative to that of the commensurate long range ordered state at the lowest temperatures, and it coexists with the incommensurate Bragg peaks below T_c2. The integrated scattering over both commensurate and incommensurate positions evolves continuously with decreasing temperature for all temperatures below T* ~ 130 K.Comment: To appear in Physical Review B: Rapid Communications. 5 page

Gains from the upgrade of the cold neutron triple-axis spectrometer FLEXX at the BER-II reactor

The upgrade of the cold neutron triple-axis spectrometer FLEXX is described. We discuss the characterisation of the gains from the new primary spectrometer, including a larger guide and double focussing monochromator, and present measurements of the energy and momentum resolution and of the neutron flux of the instrument. We found an order of magnitude gain in intensity (at the cost of coarser momentum resolution), and that the incoherent elastic energy widths are measurably narrower than before the upgrade. The much improved count rate should allow the use of smaller single crystals samples and thus enable the upgraded FLEXX spectrometer to continue making leading edge measurements.Comment: 8 pages, 7 figures, 5 table

Social Studies Content Reading about the American Revolution Enhanced with Graphic Novels

Graphic novels can contribute to effective content area reading on social studies topics such as the American Revolution. This action research study’s purpose was to examine student recall of facts, enjoyment of reading, and interest in the topic when using graphic novels as compared to illustrated nonfiction prose in social studies content area reading. Twenty-two fifth grade students (13 females, 9 males) in a public school in a Midwestern state participated in the study. Half of the students read about the Boston Massacre and Patrick Henry through graphic novels and read about Paul Revere and the Boston Tea Party with illustrated nonfiction texts, with the other half doing the opposite. The mean number of correct ideas recalled by students two weeks after reading two books in the graphic novel condition was 8.6 compared to 7.1 for the nonfiction prose condition with a medium effect size. Students rated their reading enjoyment significantly higher in the graphic novel condition indicating that graphic novels should be employed more often into the school curriculum. Suggestions for integrating graphic novels into the curriculum are provided along with other ways to take action

Suppression of the commensurate spin-Peierls state in Sc-doped TiOCl

We have performed x-ray scattering measurements on single crystals of the doped spin-Peierls compound Ti(1-x)Sc(x)OCl (x = 0, 0.01, 0.03). These measurements reveal that the presence of non-magnetic dopants has a profound effect on the unconventional spin-Peierls behavior of this system, even at concentrations as low as 1%. Sc-doping suppresses commensurate fluctuations in the pseudogap and incommensurate spin-Peierls phases of TiOCl, and prevents the formation of a long-range ordered spin-Peierls state. Broad incommensurate scattering develops in the doped compounds near Tc2 ~ 93 K, and persists down to base temperature (~ 7 K) with no evidence of a lock-in transition. The width of the incommensurate dimerization peaks indicates short correlation lengths on the order of ~ 12 angstroms below Tc2. The intensity of the incommensurate scattering is significantly reduced at higher Sc concentrations, indicating that the size of the associated lattice displacement decreases rapidly as a function of doping.Comment: 7 pages, 5 figure

Instability of Magnons in Two-dimensional Antiferromagnet at High Magnetic Fields

Spin dynamics of the square lattice Heisenberg antiferromagnet, \BaMnGeO, is studied by a combination of bulk measurements, neutron diffraction, and inelastic neutron scattering techniques. Easy plane type antiferromagnetic order is identified at $T \le 4.0$ K. The exchange interactions are estimated as $J_1$ = 27.8(3)${\mu}$eV and $J_2$ = 1.0(1) ${\mu}$eV, and the saturation field $H_{\rm C}$ is 9.75 T. Magnetic excitation measurements with high experimental resolution setup by triple axis neutron spectrometer reveals the instability of one magnon excitation in the field range of $0.7H_{\rm C} \lesssim H \lesssim 0.85H_{\rm C}$.Comment: 5 pgase, 5 figuers, to be published in PRB R

Luttinger-Liquid Behavior in the Alternating Spin-Chain System Copper Nitrate

We determine the phase diagram of copper nitrate Cu(NO$_3$)$_2\cdot$2.5D$_2$O in the context of quantum phase transitions and novel states of matter. We establish this compound as an ideal candidate to study quasi-1D Luttinger liquids, 3D Bose-Einstein-Condensation of triplons, and the crossover between 1D and 3D physics. Magnetocaloric effect, magnetization, and neutron scattering data provide clear evidence for transitions into a Luttinger liquid regime and a 3D long-range ordered phase as function of field and temperature. Theoretical simulations of this model material allow us to fully establish the phase diagram and to discuss it in the context of dimerized spin systems.Comment: 5 pages, 4 figure